Religion is a major factor for me, actually. Even if the girl matches every other preference of mine, I still couldn't marry her. I'm sorry if I sound like a jerk, but the belief that my beloved wife would go to hell when she died would drive me insane. Then there's the upraising of the children to consider - if my kids were raised as Christian, they would believe that their mother would be going to Hell when she died, which would be some kind of guilty-tripping awful (and would possibly strain family bonds); if they were raised in a different religion (or as atheists), then I'd feel awful because I'd think that they're going to Hell, too.
So, yeah. That's just the way how it is for me.
What will Generation VI bring the metagame?
I'm hoping for a large helping of the first option along with a healthy smattering of the third option.