My girlfriend and I work together. So does a guy she is very close to. They are really close friends, not a problem, the problem is they had some sort of relationship. She says no intercourse ever. I some what believe that but she has also told me it was a "somewhat physical relationship" also. She is still pretty close to him. By that I mean she eats lunch with him in his office, behind closed door. Talks all the time to him. Never tells me anything as to what they talk about. She says she loves only me and not him. She also refuses to change the relationship at all. I feel like it's a slap in the face everyday at lunch. I've told this and we only fight. What should I do or how should I approach this?
I should add that she was very reluctant to tell him about us in the beginning and he was extremely jealous of our relationship when he did find out.