Regardless, gay marriage is not going to go away. This is because gay people are not going to go away and conservatives should stop blinking and rubbing their eyes in the hope that, when they re-focus, homosexuals will be missing from the picture. The two most interesting and persuasive people on the pro-side of the argument are Jonathan Rauch and Andrew Sullivan. They make very lucid and fairly conservative arguments in favor of gay marriage. Their case is fairly straightforward and by now pretty familiar to anyone paying attention to such things.
Marriage is a civilizing institution.
It civilizes heterosexual young people, especially men. It encourages stability and monogamy. And it would have the same effect on gay men too. Barring gays from the institution of marriage is not merely discriminatory and unfair on its face, it is also unwise social policy because society has an interest in civilizing gay people too. Refusing gays full admittance into this fundamental institution only encourages marginal and self-destructive behavior.