Hmm..
Tricky situation there. First of all it is really hard for me to believe that the girl "loves" you that deeply and she hasn't even seen you. Call me cynic but it might be infatuation at the best. Do you have a GC? Does the girl want to come to US hence why she is ditching her ex?

Those are cynical questions but worth pondering. Do you mind doing an experimentation? First week, tell the girl that you aren't happy with your work. Second week tell her that you are thinking of quitting and you don't like in general in USA. Third week tell her that you are coming back to Nepal for good. She how she responds, she might not exactly say goodbye, but her response will indicate her intentions. If she is happy for you to come back (rather than neutral) then the girl is yours, don't give up. If not, let the other dude get her, they both will be happy.