his girlfriend may be giving off a hard time about having you as his friend, she may be the one threatened here by yours and his relationship in the past. He may avoid you because he doesn't want to tell you he's letting his girlfriend call all the shots in their relationship. He has decided he values the relationship of others more than the one he had with you. So, yeah of course that hurts alot.
To tell a little introduction to the story. He was someone who seems to like and care, and he said that he & I are close friends. ...but this year, I noticed that his attitude changed especially towards me since he started having a girlfriend. I don't know why it seems so hard for him to meet me even if it's like for a lunch and talk...but it is so easy for him to meet his friends especially his girlfriend. Even something, a decision he said he'd do which made me feel glad and less lonely...he changed that decision and I feel not just sad, but hurt. I asked him twice if I will meet him again, if I don't go to the weekly chat where I used to meet him with other people...but he never did answer that question. Honestly, I don't understand him anymore and I feel like the words he said especially about being close/important friend...is a lie. Very angry and upset.