<human>: My fiance (Anne) and I are set to get married in the fall of 2017. I love her very much and truly want what's best for her. We have a great group of friends, and many of them mutual from college.

Backstory: My fiance had a brutal falling out with her senior year roommate (Julie). They both feel mutually disrespected and aren't on speaking terms. Most of my friends didn't pick sides and stayed friends with both Julie and Anne (albeit never all in the same room). One friend (Dave) stayed particularly close to both of them and considers them both very close friends to this day.

Today: Anne saw pictures of Dave from over the 4th of July weekend with him on vacation with Julie and some mutual friends. She did some snooping and saw they have remained extremely close over the years. Anne was unaware how extensive Dave and Julie's friendship had been. She is very hurt and feels betrayed by Dave. She considered him one of her bestfriends and can't understand how he can continue to associate with someone who has caused her so much pain.

It came to a head today when Anne texted Dave today saying they were not going to be friends going forward. Dave is devastated and wants to keep Anne as a close friend.

Reddit, I want all my friends and family happy at my wedding next year, how can I help resolve this?

Can you condense the text into a few key points?
<bot>: Fiance feels betrayed by one of her bestfriends/my groomsman over staying friends with and ex/friend of hers.