“We are loving, committed and faithful couples just like anyone else.” If you’ve paid the slightest bit of attention to the same-sex marriage debate, you’ve heard this very statement in some iteration. It’s not true by some important measures though.

Same-sex male couples are dramatically more likely to be unfaithful than heterosexual couples.
Committed lesbian relationships are more likely to break up than both male-male and opposite-sex couples, by dramatic margins.

Those are two very important differences, unarguably judging the “we’re no different” dogma incorrect. What support is there for these stark differences?

First, it should be noted that the research is strong and numerous enough that a recent and very provocative Atlantic cover story on what straights could learn from gay marriage couldn’t ignore it. Liza Mundy, the article’s author, doesn’t appear to have a conservative bone in her body, yet she is fair and straight-up honest with the research on the nature of committed same-sex relationships.

More Fragile – Mundy explains that studies have found “higher dissolution rates among same-sex couples” in Scandinavia – one of the world’s most gay-friendly cultures — than married heterosexual couples. This study, published in Demography, found that even though same-sex couples enter their legal unions at older ages — a marker related to greater relational stability – male same-sex marriages break up at twice the rate of heterosexual marriages.  And the break-up rate for lesbians? A stunning 77% higher  than the same-sex male unions! When controlling for possible confounding factors, the “risk of divorce for female partnerships actually is more than twice than that for male unions.”  Mundy did not give her reader these important specifics from this study. Other studies show the same things.

A study of two generations of British couples (one born 1958, the other 1970) in same-sex cohabiting, opposite-sex cohabiting and opposite-sex marriage relationships found the same-sex relationships dramatically more likely to break up than the opposite-sex cohabiting and married relationships. The probabilities of the various relationships surviving to the 4 and 8 year anniversaries are dramatic (p. 981):

Reaching Anniversary Same-SexCohab Opposite-Sex Cohab Opposite-Sex Married
4 years 37% 67% 88%
8 years 25% 60% 82%

The author explains the magnitude of his findings “are consistent with previous research in other countries.” (p. 984) There were no significant differences between the two generational cohorts, indicating that issues of past social stigma and growing social acceptance had no meaningful effect on relational longevity.

Other studies – conducted by celebrated lesbian scholars – find notable instability in lesbian homes, even those with children. The current National Longitudinal Lesbian Family Study (NLLFS) found “a significant difference” in family dissolution rates when comparing lesbian with mother/father headed families, 56% and 36% respectively. (p. 1201)

Another research study by two celebrated gay-friendly scholars, highlights a major comparative study between hetero and lesbian homes where, in the 5-year period of the study, 6 of the 14 lesbian mother-headed homes had broken up compared to only 5 of the 38 mom/dad headed homes. (p. 11) These scholars creatively explains that this stability imbalance is likely due to the “high standards lesbians bring to their intimate unions…” (p.12)

It is likely that women tend to be more relationally intense. It’s one thing when half a partnership feels the need to “talk about our relationship” and the other not so much. It provides a helpful and healthy balance. It is another when, as Mundy admits, “Lesbians…tend to discuss things endlessly.” Few relationships can endure such relational intensity and it appears as if they don’t.

And Mundy points something else predictable in lesbian relationships. In fact, its consistency has earned it a name in the LGBT community: lesbian bed death. Seriously.  This is the truth that sexual interest and frequency in many long-term lesbian relationships tends to decline considerably and even die over the years. However, she puts a positive spin on it with this “increased-relational intensity-among-lesbians” motif, explaining, “Lesbians may have had so much intimacy already that they didn’t need sex to get it.” As if one type of intimacy can fulfill one’s desire for all others.

So what about the guys?

More Infidelity – Men in same-sex, long-term relationships are dramatically more likely to be unfaithful to their partners. But that depends on how you define “fidelity”.  It is common in male-male relationships to differentiate between “fidelity” and “monogamy.” Monogamy is having sex with only one person: your partner. Fidelity however is often living according the rules made about how extra-relational sexual hook-ups will take place. A partner who runs afoul of this extracurricular agreement will be deemed unfaithful. How many hetero couples do you know who have such an agreement worked out in their marriage? We’ll see in a moment.

A noted 2010 study on non-monogamy in long-term gay relationships by two gay-affirming scholars — the Couples Study — observes in their report’s first sentence: “…non-monogamous relationships are very common in the gay community…” Their data showed that of the non-monogamous, long-term couples in their study, 42 percent made an arrangement for outside-sexual relationships within the first three months of the relationship’s beginning and by the end of the first year, that number increased to 49 percent. At the seventh anniversary mark, an additional 24 percent of gay couples adopted such agreements. So such agreements are increasingly made as these relationships grow longer.

The Atlantic piece is notes this as well; explaining that after the AIDS crisis, “gay male couples are more monogamous than they used to be, but not nearly to the same degree as other kinds of couples.” One study Mundy cites asked those in various relationships whether they had any agreed-upon rules permitting extra-curricular activities. The differences were astonishing. Only 4% of male/female couples had them compared to 40% of gay men in legally recognized unions and 49% in long-term cohabiting unions.

Another widely respected investigation, found that only a third of gay couples had monogamous agreements and truly honored them with no outside sex. In fact, it found that in the openly nonmonogamous gay relationships, the frequency of extra-dyadic sex from its start ranged from 2 to a whopping 2,500 separate incidents. The median was a remarkable 41.5 extracurricular incidents since the relationship’s beginning. Frequency in the last year was startling was well, ranging from 0 to 350 occurrences of outside sex, with a median of 8 incidences in the last twelve months. Even those who pledged true monogamy, the range was from 1 to 63 “slip-ups” with a median of 5. Five “slip-ups” are not slip-ups. The corresponding numbers for men in heterosexual marriages are microscopic in comparison.

In 2010, the New York Times highlighted the commonality of such agreements among serious male-couples explaining, “none of this is news in the gay community, but few will speak of it publicly.”  (On the “let’s keep this secret to ourselves” nature of this issue in the LGBT community, carefully read the soul-bearing note at the bottom of the CouplesStudy homepage.)  And the older gay relationships get, the more likely they are to have such relationships, likely contributing to their duration.

It is proposed by some that gay male relationships last longer than lesbian relationships because they are able to meet two primary interests simultaneously: 1) having a primary partner to share their life and home with, while 2) also having an outlet for exploring greater sexual diversity and opportunity. This is distinct in the undisciplined masculine nature. We find the basic female nature working against the longevity of lesbian relationships: her relational intensity. It is harder for women to work out an agreement beyond their primary relationship to get the greater sense of relational connectedness they seek.

By any measure, these are very different kinds of relationships compared to those of long-term heterosexuals. As such, it is difficult to say with honesty that serious gay and lesbian relationships are just like heterosexual relationships. A substantial body of research and articles written in idealistic support same-sex relationships makes this consistently clear, beyond any honest debate.