Well....
Lets look at the fundmental principles of WHY God has "rules" regarding relationships.
1. Teen pregnancy is a problem.
2. STD's are a problem
3. Getting too "in love" can lead to suicide if one decides to break the relationship. I mean think of it... a guy is madly in love with a girl. MADLY. and she breaks up with him, and starts dating a guy that he knows, but he really doesn't like him at all. then she gets engaged, and at the wedding reception, her old BF dances with her, and starts crying and crying cuz he is still in love with her. but there is nothing she can do, cuz she is married to someone else. and worse off, he has the following thought in his mind "she is going to be having sex with the girl i really, really love, tonight. while i lay in bed crying and crying and crying cuz i love her so much. also he has to think "she will be starting a family him, and here i am left behind, feeling lonely, depressed, etc. (THAT DOES HAPPEN, AND IT IS NOT FUNNY. THAT WOULD BE MY ULTIMATE NIGHTMARE.)
4. also, when you are with your wife / GF, and she has dated someone else and gone too far (and you know she has) the thought "i am exploring a cave that another man has been in" wanders through your mind. I would hate that, also. (sorry if that's a liitle risque)
so, all that being said, remember this... we are not under the law anymore, rather grace.
do not get like i used to be... and feel the need to confess every little thing as sin. That is somewhat "legalism"
remember... God loves you so much.... more than a guy who's madly, madly, madly, madly in love with a girl. If it is hard for the guy to get angry at the girl..... IMAGINE HOW HARD IT IS FOR GOD TO GET ANGRY AT HIS FOLLOWERS (not the ones who rebel against him though. thats another story)