Girlfriends are for suckers and people still in grade school. BUT if you fit in one of those categories, you're in a relationship for a reason, and not constantly worrying about your girlfriend cheating is priority number one, so answer B without a doubt. If you choose answer A, then you're in a relationship for the wrong reasons and you should be single and fucking random girls, not being ones bitch. A WILL cheat on you, it's inevitable that she will meet someone more attractive and better off in life than you. Then you're left out in shitter(probably crying like a bitch, since you were her bitch the whole time) while she moves on to her next phase and you move back to porn on the internet and being the lonely guy that will never find love.