Ok this isn't really about dating but I hope you guys can give me a bit of help anyway.

Basically I have become really good friends with an ex of mine, and we hang out as often as our schedules allow (I'm at work monday to friday while she's at college, and she works saturday so we don't have much time. Obviously she spends a lot of time with her bf too so we only see eachother a few times a month).
The problem is her current boyfriend. My friend tells me that her bf used to be fine with her seeing me cos there was complete trust in the relationship and they both love each other. However today it screwed up a bit. I went to visit her in the early afternoon and she had already told her bf I was coming (she tells him everything). His reaction was kinda ambiguous which is unusual, cos he was always completely fine with it in the past. Anyway as the evening came and she got a text from him in which he hinted quite obviously that he wasn't happy with me being there. She decided to call him about it, and when she raised the subject he apparently hung up on her.

Now neither of us know what to do because we both consider our friendship quite valuable (she's one of my best female friends) but of course she doesn't want to upset her boyfriend.

She's seeing him tomorrow and said she'd talk to him about it and let me know the outcome.

Just wondering what anybody's thoughts are on this. By the way I no longer have romantic feelings for her and I assume she doesn't for me either so that's not really an issue. The issue is the potential loss of a great friendship. If her boyfriend doesn't want me seeing her any more do you think its worth sacrificing our friendship?