What do guys look for in a girlfriend? (Teenage guys only please)?

Okay, so I have this ex and I broke up with him a while ago but now I want him back.

The only problem is that he's going out with this girl who I can't stand at all and he knows that I hate her.

But he's a sex addict and she's a virgin and trust me she won't put out any time in there relationship so he won't get laid, which he wants too.

So how would I get my ex to want me back and dump this ***** for me?What do guys look for in a girlfriend? (Teenage guys only please)?
uhh, hes probably with this girl to get back at you anyway (unless this has been a long relationship with them both) and he most likely still has feelings for you. i would tell him how you feel, and tell him that you were stupid for breaking up with him and that after all this time you cant be without him.. and then thats will definitely make him think long and hard about it and hopefully for you he will take you back (p.s only say those things if you mean it though)