Delineating the Boundaries Between Nonmonogamy and Infidelity: Bringing Consent Back Into Definitions of Consensual Nonmonogamy With Latent Profile Analysis

Figures & data

Table 1. Demographics of sample

Demographic Dimension Subsamples	N	% in full sample	% in males	% in females
Full sample	1658
Gender Identity
Male	485	29.25%
Female	1157	69.78%
Non-binary/Gender-fluid/Other	16	0.97%
Age
18-20 yrs	232	13.99%	10.72%	15.35%
21-24 yrs	401	24.19%	19.18%	26.26%
25-29 yrs	336	20.27%	20.00%	20.38%
30-39 yrs	382	23.04%	28.66%	20.72%
40+ yrs	301	18.15%	21.24%	16.88%
Race
White	1304	78.65%	77.94%	78.94%
Asian	143	8.62%	9.07%	8.44%
Black	95	5.73%	6.60%	5.37%
Other	105	6.33%	5.98%	6.48%
Ethnicity
Non-Latino/Hispanic	1485	89.57%	89.28%	89.68%
Latino/Hispanic	138	8.32%	8.87%	8.10%
Education
GED/HS diploma or less	146	8.81%	9.69%	8.44%
Some college/AA degree/Trade certificate	590	35.59%	35.88%	35.46%
Bachelor’s degree	587	35.40%	34.02%	35.98%
Graduate degree	332	20.02%	20.41%	19.86%
Income
0 to $29,999	411	24.79%	25.15%	24.64%
$30,000 to $59,999	505	30.46%	34.23%	28.90%
$60,000 to $89,999	310	18.70%	17.53%	19.18%
$90,000 or more	415	25.03%	22.89%	25.92%
Sexual Orientation
Heterosexual	987	59.33%	63.30%	57.97%
Heteroflexible	285	17.19%	10.72%	19.86%
Bisexual	190	11.46%	8.25%	12.79%
Homosexual	196	11.82%	17.73%	9.38%
Relationship Status
Casually dating (dating more than 1 person)	254	15.32%	18.97%	13.81%
In a committed relationship	509	30.70%	30.10%	30.95%
Long-term committed relationship	436	26.30%	21.86%	28.13%
Engaged	85	5.13%	4.33%	5.46%
Married	374	22.56%	24.74%	21.65%

Note: Sexual orientation was assessed with the 2-item Multidimensional Sexual Orientation Classification System (MSOCS: Legate & Rogge, 2019). Respondents were grouped into male and female groups based on their gender identities rather than their sex at birth (e.g., trans-males were grouped with cis-gendered males).

Table 2. Model fit across latent profile analyses specifying from 1 to 5 latent classes

Classes Specified	# of free parameters	Log- likelihood	AIC	BIC	BIC N-adj.	LMR-LRT p	BLRT p	Entropy	# classes with n<40
FULL SAMPLE
2	34	-23715	47498	47682	47574	<.0001	<.0001	0.974	0
3	48	-22943	45982	46242	46089	0.003	<.0001	0.954	0
4	62	-22273	44669	45005	44808	<.0001	<.0001	0.978	0
5	76	-21830	43811	44223	43981	0.003	<.0001	0.956	0
6	90	-21295	42770	43258	42972	0.098	<.0001	0.972	0
7	104	-20975	42158	42722	42391	0.068	<.0001	0.97	0
IN 485 MEN
2	34	-7098	14264	14406	14298	0.0664	<.0001	0.964	0
3	48	-6843	13782	13983	13830	0.0007	<.0001	0.946	0
4	62	-6630	13384	13643	13446	0.0008	<.0001	0.972	0
5	76	-6492	13136	13454	13213	0.0139	<.0001	0.963	0
6	90	-6360	12901	13277	12992	0.0728	<.0001	0.97	0
7	104	-6233	12673	13108	12778	0.0109	<.0001	0.974	0
IN 1173 WOMEN^1
2	34	-16539	33145	33317	33209	<.0001	<.0001	0.978	0
3	48	-16015	32127	32370	32217	0.0001	<.0001	0.964	0
4	62	-15554	31232	31546	31349	0.1504	<.0001	0.965	0
5	76	-15217	30586	30972	30730	<.0001	<.0001	0.978	0
6	90	-14822	29824	30280	29994	<.0001	<.0001	0.976	0
7	104	-14608	29425	29952	29622	0.0018	<.0001	0.974	0

Note: The table presents the fit statistics from LPAs run in the full sample (top section), in men only (middle section), and in women¹ only (bottom section), demonstrating that the fit indices continued to suggest a 5 class solution in both major gender groups. The solution selected to have the most parsimonious fit has been bolded to ease interpretation. AIC = Aikaike’s information criterion, BIC = Bayesian information criterion, N-adj. = BIC adjusted for sample size (lower numbers on the AIC and BIC indices suggest better fit), LMR-LRT p = Lo-Mendel-Ruben likelihood ratio test significance level, BLRT p = Bootstrap Likelihood Ratio Test significance level (a significant LMR-LRT or BLRT suggests that the current solution accounts for significantly greater amounts of between-person differences than the solution with one fewer classes specified). Entropy = the average probability of each participant belonging to the class to which they were ultimately assigned, thereby representing clarity of classification for each solution (higher numbers suggest a better fit with numbers above .9 suggesting excellent fit). ¹ So as to include all respondents in one of the two groups, the 16 transgender/non-binary/other respondents were combined with the women when running the final set of LPAs above.

Table 3. Characterizing the latent commitment classes

					Latent Classes
Class of Constructs					Monogamous		Nonmonogamous
Specific Constructs Examined				Full Sample	MONOG - min EDSA	MONOG - low EDSA	OPEN CNM	PART-OPEN	ONE SIDED	Omnibus test of differences across classes	Effect Size of Greatest Pairwise Diff (Cohen’s d’s)
Number of respondents:				1,658	629	496	128	218	187
LATENT PROFILE ANALYSIS PREDICTORS						Within-Group Percentages or Means
Global Structure Question
R1: Monogamous				72.26%	95.7%^A	87.00%^B	7.70%^E	49.10%^C	26.40%^D	χ ^2(4)=758*	3.1
R2: Primarily one partner engages in EDSA				10.13%	1.00%^D	5.90%^C	11.70%^BC	18.20%^B	40.90%^A	χ ^2(4)=299*	1.4
R3: Open relationship - EDSA together				4.40%	0.30%^C	4.70%^BC	21.70%^A	8.60%^B	0.70%^C	χ ^2(4)=143*	0.93
R4: Open relationship - EDSA separately				7.30%	0.20%^D	1.90%^C	53.20%^A	12.20%^B	8.50%^B	χ ^2(4)=461*	1.88
R5: Not committed				5.91%	2.80%^C	0.50%^D	5.70%^BC	11.90%^B	23.50%^A	χ ^2(4)=149*	0.89
Recent EDSA
Reported own EDSA in last 2 months				18.79%	3.30%^D	13.70%^C	63.30%^A	34.20%^B	60.70%^A	χ ^2(4)=400*	1.77
Reported partner EDSA in last 2 months				12.96%	2.20%^D	8.70%^C	58.50%^A	27.20%^B	28.00%^B	χ ^2(4)=300*	1.74
Triple-C Components
CN	CF	CM
x	x		Own desire for monogamy	4.72	5.28^A	5.23^A	2.39^D	4.24^B	3.66^C	F(4,1651)=327*	3.28
x	x		Partner’s desire for monogamy	4.96	5.52^A	5.54^A	2.36^D	4.36^B	3.99^C	F(4,1646)=421*	4.16
	x		Own distress at partner’s EDSA	3.69	3.45^B	4.76^A	1.65^C	3.53^B	3.18^B	F(4,1638)=78*	1.83
	x		Partner’s distress at own EDSA	2.34	1.80^C	2.65^B	1.31^D	2.79^B	3.45^A	F(4,1640)=49*	1.34
	x	x	Own awareness of partner’s EDSA	3.16	1.08^D	5.38^A	5.47^A	3.51^B	2.18^C	F(4,1642)=1553*	7.46
	x	x	Partner’s awareness of own EDSA	3.16	1.03^D	5.68^A	5.71^A	3.58^B	1.32^C	F(4,1648)=11699*	19.82
		x	Active communication about EDSA	2.72	1.33^E	4.07^B	5.01^A	3.05^C	1.79^D	F(4,1641)=363*	3.33
PROXIMAL RELATIONSHIP FACTORS
Less than 1 year				30.30%	22.81%^C	31.65%^AB	24.41%^BC	41.94%^A	42.39%^A	χ ^2(4)=46*	0.38
1 to 5 years				44.00%	46.60%^A	48.00%^A	37.80%^AB	41.00%^AB	32.10%^B	χ ^2(4)=18*	0.29
More than 5 years				25.70%	30.60%^A	20.40%^B	37.80%^A	17.10%^B	25.50%^AB	χ ^2(4)=34*	0.48
Living together				43.68%	50.56%^A	43.43%^AB	54.33%^A	26.27%^B	34.22%^B	χ ^2(4)=51*	0.59
Relationship satisfaction				15.63	16.03^A	16.92^A	16.67^A	13.96^B	12.09^C	F(4,1651)=61*	1.25
Dedicated (top 3 of 6 answers)				74.60%	83.50%^A	84.20%^A	75.80%^A	54.60%^B	42.20%^B	χ ^2(4)=199*	0.93
Low Affection (0-4x in last 2 weeks)				28.80%	29.90%^B	22.00%^C	18.00%^C	33.50%^AB	45.50%^A	χ ^2(4)=47*	0.59
Frequency of sexual activity w partner				1.18	1.01^C	1.30^AB	1.28^ABC	1.50^A	1.05^BC	F(4,1647)=10*	0.44
High sexual satisfaction (top 2 of 6)				45.10%	46.40%^A	54.50%^A	49.60%^A	29.40%^B	31.20%^B	χ ^2(4)=56*	0.48

Note: MONOG – min EDSA = Monogamous relationships with minimal extra dyadic sexual activity; MONOG – low EDSA = Monogamous with low amounts of recent EDSA; CNM OPEN = Open relationships that could be classified as consensual nonmonogamy; PART – OPEN = Partially open relationships; ONE SIDED = Relationships with Primarily One-Sided EDSA; R1-R5 = the response options offered for the question asking participants to identify the relationship commitment structure of their relationship. CN = Consent, CF = Comfort, CM = Communication. Given the number of planned contrasts, a p = .001 significance threshold was used for the omnibus tests and a p = .005 threshold for the subsequent pairwise comparisons to help constrain the experiment-wide alpha level. Different superscripted letters indicate significant differences between classes emerging from the pairwise comparisons. Cohen’s d’s were calculated for the largest difference between group means on each variable (row) to give an estimate of a standardized effect size. * = p < .001, † = p < .005. The highest means or percentages in each row have been bolded to facilitate interpretation of the results.

Table 4. Differences across latent commitment classes on background, demographic and outcome factors

		Latent Classes
Class of Constructs		Monogamous		Nonmonogamous
Specific Constructs Examined	Full Sample	MONOG - min EDSA	MONOG - low EDSA	CNM OPEN	PART-OPEN	ONE SIDED	Omnibus test of differences across classes	Effect Size of Greatest Pairwise Diff (Cohen’s d’s)
Demographic Factors	Within-Group Percentages or Means
Male	29.25%	23.05%^B	29.03%^AB	35.94%^A	37.16%^A	36.90%^A	χ^2(4)=26*	0.28
Age	30.00	31.01^AB	27.79^C	32.57^A	29.26^BC	31.56^AB	F(4,1647)=11*	0.52
Years of education	15.20	15.52^A	14.71^B	15.39^A	15.22^AB	15.30^AB	F(4,1650)=8.2*	0.33
White	78.65%	81.56%^AB	75.00%^B	88.28%^A	75.23%^B	75.94%^B	χ ^2(4)=17*	0.32
Background Factors
Sexual Orientation (MSOCS)
Heterosexual	60%	70.27%^A	64.72%^A	24.22%^C	43.12%^B	52.94%^B	χ ^2(4)=130*	0.58
Heteroflexible	17%	11.76%^C	14.52%^BC	32.03%^A	22.48%^AB	26.20%^A	χ ^2(4)=50.3*	0.35
Bisexual	11%	7.79% ^B	9.68% ^B	28.13%^A	16.97%^AB	10.70%^B	χ ^2(4)=51.6*	0.36
Homosexual	12%	10.17%	11.09%	15.63%	17.43%	10.16%	χ ^2(4)=10.7	0.16
High sociosexual orientation (top 4 answers out of 9)	15.30%	7.30%^C	9.30%^C	42.50%^A	20.90%^B	32.80%^A	χ ^2(4)=167*	0.84
High sexual sensation seeking (top 3 answers of 6)	24.30%	16.00%^B	21.30%^AB	43.70%^A	29.90%^A	40.70%^A	χ^2(4)=81*	0.53
Attachment Avoidance	2.50	2.37^B	2.30^B	2.25^B	3.01^A	3.06^A	F(4,1596)=38*	0.84
Outcomes – Psychological
Loneliness	2.48	2.31^B	2.39^B	2.34^B	3.04^A	2.79^A	F(4,1595)=21*	0.65
Psychological distress	2.37	2.29^B	2.35^B	2.24^B	2.70^A	2.44^AB	F(4,1563)=4.3†	0.34
Outcomes – Behavioral
Geosocial networking app use	22.44%	9.22%^C	18.15%^B	41.41%^A	43.12%^A	41.18%^A	χ ^2(4)=186*	0.84
Heavy drinking/drug use (1-2x or higher on average across all heavy use/impairment items in last 2 mo)	21.20%	12.70%^C	21.60%^B	15.70%^BC	37.50%^A	34.10%^A	χ ^2(4)=79*	0.57
Condomless sex with new partners in last 2 mo (among a subset of 443 of the Ps actively seeking new partners)	50.79%	30.99%^B	38.78%^B	52.56%^AB	65.74%^A	60.23%^A	χ ^2(4)=30*	0.66
Sexually Transmitted Infections - Lifetime	25.38%	21.29%^B	20.59%^B	37.19%^A	34.76%^A	33.71%^A	χ ^2(4)=37*	0.72

Note: MONOG – min EDSA = Monogamous relationships with minimal extra dyadic sexual activity; MONOG – low EDSA = Monogamous with low amounts of recent EDSA; OPEN – CNM = Open relationships that could be classified as consensual nonmonogamy; PART – OPEN = Partially open relationships; ONE SIDED = Relationships with Primarily One Sided EDSA; Ps = Participants. MSOCS – the Multivariate Sexual Orientation Classification System (Legate & Rogge, 2019). Given the number of planned contrasts, a p = .001 significance threshold was used for the omnibus tests and a p = .005 threshold for the subsequent pairwise comparisons to help constrain the experiment-wide alpha level. Different superscripted letters indicate significant differences between classes emerging from the pairwise comparisons. Cohen’s d’s were calculated for the largest difference between group means on each variable (row) to give an estimate of a standardized effect size. * = p < .001, † = p < .005. The highest means or percentages in each row have been bolded to facilitate interpretation of the results.

Figure 1. Latent relationship structures extracted by LPA. S = subjects referring to themselves; P = subjects’ perceptions of their romantic partners; Monog = Monogamy; EDSA = extra dyadic sexual activity; MONOG – min EDSA = Monogamous relationships with minimal amounts of recent extra-dyadic sexual activity; MONOG – low EDSA = Monogamous relationships with low amounts of recent EDSA; OPEN – CNM = Open relationships that could be classified as consensual nonmonogamy.

Figure 2. The COMMIT4: a four-item reconstruction of latent classes derived from decision tree analyses. Decision tree analyses (a form of machine learning) were conducted using the DecisionTreeClassifier from the scikit-learn package (Pedregosa et al., 2012). The tree was constrained to five leaf nodes corresponding to the five desired latent classes (See the methods section for the full range of responses offered for question 2). The COMMIT4 classification system was derived via a machine learning decision tree algorithm to represent the most parsimonious method of recreating the 5 latent classes with the fewest items. It was therefore not intended to represent substantive findings (nor should it be substantively interpreted), but instead represents a practical application for future research.

Legate, N., & Rogge, R. D. (2019). Identifying basic classes of sexual orientation with latent profile analysis: Developing the multivariate sexual orientation classification system. Archives of Sexual Behavior, Online Release, 1–20.

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