Some countries or state have been accepting this kind of marriage. Here in the Philippines, we do not recognize it as legal or something like that. How about in your country?
Actually, I am in favor of same sex marriage for the very reason that we should give other people the chance to be happy by choosing the person they want to spend their life with, regardless of the gender. We may never understand them because we aren't in the same situation as them. So, the best thing to do is to respect their decision.