So whose name is the new apartment in ? If the new apartment is in his name he can tell you to move out and you have to move out. Even if the apartment is in both of your name and if his girlfriend is staying with him and in his room; then there is nothing you can do about it. If you go and complain that to your apartment; they will not do anything (worst case scenario, they might terminate his lease for non compliance but that is very unlikely). But if the lease stated clearly that you can't have more than one guest for 40 days, it's up to you to make sure you stay in compliance (if the lease is in your name too).

Well if the lease is on your and your friends name then he can't say tell you to move out. And he should grown an extra pair of balls to sublease the apartment to someone else without your consent (written). But you can tell her to get out of the apartment or share the utilities/grocery/and other bills except for the room. In that case you can file the case at small claims court.  Divide the costs of living by the 3 (except for the room) and take his ass to court. 

There is nothing he can do to push you away from that Apartment until the Lease Deadline is finished until your name is in Lease . Yes you can drag him to court for harassing you to leave the apartment when you still are paying your share of Bills in time and rent in time just make sure you have enough Proofs for it . If her name is not listed in lease then she will have no rights to brag or bark about anything against you .

I know how you feel cause i have gone through similar but worst case scenario when it comes to sharing apartment with so-called friends since then i made my mind what ever happens i won't share apartment with any friends in my life . I know what i went through and i do regret each moment what i did for him .

Best solution never trust anyone and go ahead and file a case this is all i can suggest .

Kick his gf out. She is not in the lease contract. He will go too. Get another roommate.

furke is right...you have every right to kick his gf out of the apartment since her name is not on the lease..period!

Just throw her stuff out or call the cops. Also talk to ur leasing office they will help u out in most instances to find a roommate or even forgive his other half.