Neither "God" nor the Bible prevents us from doing anything. They are merely teaching and suggesting.
If you are not "free" then there is no virtue or sin. Mother Teresa deserves no praise for giving her life to serve the poor and diseased of India, unless she had a choice to do otherwise (which she did).
As I have written in this space before, people with homosexual tendencies are FREE to either succumb to them or to remain celibate, or live a "normal" life. The choice(s) they make, however, have moral implications and, if you believe the Bible, affect their prospects in the afterlife - if there is one.
Gay marriage? Knock yourself out. But recognize that (for men) entering into this institution is a public rejection of Judeo-Christian and Islamic teachings, and tells the world that you INTEND to engage in behavior that Christians, Jews, Muslims, etc., consider seriously sinful. And don't expect such people to condone that decision or pretend that it is morally neutral, when they emphatically believe otherwise.
Christians love homosexuals, but hate sin. Just as I loved my uncle who was a chronic drunk. I didn't love him any less, but I never condoned his behavior.