Right to marriage?

The advocates for same-sex marriage have done well to cast the issue as a civil rights issue. This was the key to their recent victories, especially in Iowa. As I have argued before, the issue should be about whether or not sanctioning same-sex marriage is of any benefit to society. The reason is, marriage is a three-party contract among two partners and society. Society's interest in the contract is the benefits that I have enumerated previously. No individual has a right to force society into a contract unwillingly. Until such time as same-sex couples present a convincing argument that society will benefit from entering into a contract with them, there is no civil rights issue.

However, we have reached a time where we have a few states that have legalized same-sex marriage. There is an opportunity to compare them to traditional marriages. Will gay men stay in these relationships for the long term, moderating their promiscuity? What about same-sex female relationships?

I suspect that same-sex married women will be as different from same-sex married men as their heterosexual counterparts are. They will be more likely to adopt children and stay in stable relationships, for longer periods of time. You may read studies about same-sex marriage that are limited to females or blur any distinction between male and female, but perhaps none that study same-sex male relationships. If so, would it not be fair to conclude society isn't getting anything in return for sanctioning same-sex male relationships?