There are reasons.
He's not going to be a real husband. Just part-time. Yes, I have to live with him. And, okay, I also have to share his bed. And, sure, he's the sexiest and most exciting thing to ever happen to my controlled, organized life.
But still... It's only a part-time marriage. I'm not going to give him my heart. I know what I'm doing, and I'm too smart to fall for my husband.