I know the same-sex marriage thing is passe' by now but I'd just like to say:
It's really black and white and cut and dried. You either believe in marriage or you don't.
Now if you don't believe in marriage then that's fine but stay out of the fight about who can or can't get married.
If you do believe in marriage then you must believe it's good for everyone who believes in it. If you don't think it's good for everyone who believes in it then you don't really believe in marriage and you must stay out of the fight about who can or can't get married.
It's just that simple. If you really believe in marriage then you must do everything you can to help everyone who wants marriage to get it. If you oppose anyone getting married then you don't truly believe in marriage. The only people who don't want everyone who believes in marriage to get married are those who don't really believe in marriage. Those who don't really, truly believe in marriage should just sit on their hands and keep their mouths closed during this debate. Nobody is forcing you to get married; and nobody is forcing you to stay married.
If you are married and you want to stop someone else from getting married, then you should evaluate why you are married, because you don't really believe in it, and you should consider giving it up.
If someone says to you that so-and-so should not be getting married, then you must question their belief and commitment to marriage, because they clearly don't believe in marriage.
You either believe in marriage or you don't.
You are with us or against us.
It's that simple.