you listen to your father too much. frankly, the way i see it, you dont love her enough. when i was in a relationship once, i learned how its like to miss someone so badly that she is all i can think of. if i were in your gf's shoes i would definitely not be happy with you.

you were still doing your phD while she remained loyal to you. do you know how many long distance relationships that i've seen fail? anyway do you think shes trying to get herself pregnant? sex with someone you love is called love. not sex (in my opinion). keep in mind she was with you, she fell for you before you accomplished anything. she stayed on with you for so long. and now you just let her slip.

seriously, if you still have any love for her, swallow your ego and throw away your status and try to get her back. there are many things that money can't buy