I personaly dont think you should wait til marriage. I am involved and dont think twice about it. Love is something that makes sex better but it doesnt have to be there for all people.
I used to think that sex should only be if you're in love. But I've realized it depends on the situation. If both people are comfortable with it just being something that feels good then go for it. But if you lead someone to believe it's making love and not just sex when all you want is to get off.. then that's wrong.