There is no reason for gay marriage. Marriages was instituted in law to foster stable relationship, outlaw unstable relationships and to foster a better environment to raise children.
I totally agree, but there's no use saying that to someone who promotes it. But I do hate when people try to justify their causes by touting the "free society" concept. I guess they think we're all free to do as we please. Besides any group of people who thinks NAMBLA is okay has a serious moral problem.
OK--let's assume your premises are correct.
IF it could be demonstrated that same-sex marriages would result in more "stable relationships" -- would you still be opposed?
Straight couples have a very high divorce rate so apparently marriage has very little to do with "outlawing unstable relationships".
Suppose 99% of all same-sex partners have no interest in having or adopting children. Would you oppose same-sex marriage simply because 1% might express interest in raising children---even if they met all the same standards and requirements as a straight couple?