Same-sex marriage recognition at the state level was associated with more support from a spouse or partner and less psychological distress about an LGB identity, ... also finds that long-term same-sex relationships are beneficial to the health and well-being of couple members, regardless of marital status.
Key findings from the study include that state recognition of same-sex marriages is significantly associated with experiencing less motivation to conceal an LGB identity, less vigilance and fewer feelings of isolation and that marriage may also reinforce commitment within a relationship, leading couple members to feel more positively about their relationship with their partner.
(Источник:
Impact of Civil Marriage Recognition for Long-Term Same-Sex Couples)