Any sex whatsoever outside of marriage is a sin, whether one gets pregnant or not. Sex inside marriage is not a sin and is for procreation and enjoyment. You don't have to be intimate with your spouse just to have children. Homosexuality is always a sin, as the Bible says so, and even if the human laws change to allow for same-sex couples to marry, it is still a sin.
I also want to say that I don't agree with birth control or abortion. God is the giver of life. What right do we have to tell Him, "No, God, I don't want kids, but I want to have sex, so here's the deal. I'm going to take measures to prevent life, just so I can have what I want. Basically, I don't care what You want." Yeah, that's my take on it.
So, since I don't want to have children, I don't want to marry. This was off topic but since the subject was touched upon, I went there.
Sorry.