My girlfriend and I have been together for three years and I love her very much. We're not living together and we live in different cities. We see each other once or twice a week only. Our relationship has been running smoothly until about five months ago. Every time we're together we're happy and we get along well. But when we're apart she always pick a fight over the phone. She accuses me of cheating when I'm actually faithful to her. Makes me wonder if she's the one cheating.
As much as I don't want to say this, I think your gf might be the one cheating. She's just trying to turn things around and put the blame on you. Ask around. Do you have common friends who are in the same place she's at?