Homosexuality exists. Even if you "don't allow" it.
Why shouldn't gay men be allowed to marry each other? They won't become straight, if you forbid it.

You only talk about same-sex marriage of men. But because women can be homosexual too, there won't be a problem with more women having a trouble finding a partner. Women can love (and marry) women.

"the number of women is several times more than the number of men." What? No, that's just wrong.

It's a human right, not to be discriminated because of your sexual orientation.