Personally, what two consenting adults do is between them and God. I have enough to worry about keeping myself good with the Lord.
The state, however, owes it to all of us to guarantee the legality of marriage stops dead here with same sex couples. It's all about money anyway, they always could have all the love and sex they wanted. What changes is everything from healthcare plans, pension benefits and social security. All of which are at breaking point financially as it is. Same sex couples won't hurt them any, and may even help given they aren't exactly baby factories. Polygamy, however..... That will bankrupt everything and it's been waiting in the wings for gay marriage to set the precedent. Don't care about gays, but God help us if we don't stop it there.