Sounds like one of those chicks that constantly requires a boyfriend so she can get the affection and attention she needs if what you're saying about hanging around with that other dude a lot is true.
Fuck those kind of chicks, seriously, they're all fucking manipulate cunts that can't stand being alone and have nothing that makes them happy in the long term.
Girls like that are below your league, you'll get someone better.
Personally, I haven't been in a relationship in 3 years (girls have come and been around, but no actual legit, official relationship though) simply because I'm just not the type of person that wants to be around ANYONE on a frequent basis.
I just love that alone time to be able to read, play guitar, properly listen to music, watch world films and a lot of chicks just don't understand that it seems.