"and now he has a gf. i dont think shes with him for the right reasons, but i decided not to interfere. the thing is i still like him, and i dont know wat to do. should i wait for him.. or should i just move on?"
You should never build your happines on the misfortune of another person... also, be very carefull, love can be tricky.
My advice is to wait and see what is going to happen.Howewer, if the girlfriend of the guy you like is going to stay whith him more than 4 months, you should give up and find another one.