Okay so here I am, 17 and I've started this great relationship. Not only that but its my first real one. Its been 4 months and we are still pretty strong but now I'm starting to notice some things. Like how many guys she talks to, or how many guys that do stuff I would approve of. Not only that but now she's started to talk to guys behind my back... guys that are her "best friends". Now I know they can't be because she's met one of these guys once in real life and she's only friends with him because he is a drummer in a band... WHippty doooo! Well anyway I just feel a little concerned. I mean I love this girl. If I had to marry young, she be the one, But she gives me stress.Of course she sees nothing wrong with it but I mean when I'm talking to my girlfriend and someone aims to through a paper ball at her breasts, and she's cheering them on... gets me down. So I was wondering if I have something to be worried about and how do I deal with this. Ive tried asking her to stop. But she finds he way around it.

What do you mean by "pretty strong"? Are you "exclusive" with her? Do you date? If so, what do you do when you date?

If the guys are friends and they are just talking, there is nothing wrong with that.
Lots of girls have guy friends, you have to learn to trust her.

You said she "met one guy once in real life"...
Are the guys she is talking to online?

Relationships are not easy. They take work.
You need to learn to trust and not be jealous ,
That will eat you up.

How much harm would a ball of paper do if it did hit
Her breast?
And it sounds like she realized it was teasing , it may
Not be good etiquette , but is not horribly inappropriate .

People will be who they are. Asking them to stop what is normal behavior for them usually leads to trouble.
You either learn to understand it and/or deal with it,
Or leave. People don't really change much.

Actually it is you that needs to stop.

Stop trying to change her, accept her for who she is,
Or get out now.

I wish you well.