What to do with two (once) close mutual friends who aren't communicating?

I had a great friend (I’ll call her Mary) in high school and when we graduated, we went to separate schools. At university, I made a great new friend, (I’ll call her Molly). Molly and I hung out together and got along famously. Then, Mary decided to come to my university and live with me. So, Mary and Molly and I became really close friends. Mary was a bit of a wild child (think Goldie Hawn in the “Banger Sisters”) but during university, we all had a bit of that wild streak. There was a time when I met a man and we started dating and spending a lot of time together. That’s when Mary and Molly became even closer. Then all of us, including our boyfriends would hang out together.

I ended up moving away after university, and Mary went one way and Molly went the other. They kept in touch. I kept in touch. Then, Molly married. And Mary married. Everything was still okay as far as I know. Then, a few years into Molly’s marriage, Mary was in her town and called her up to meet her for dinner. Molly came to meet her and (according to Mary) was really distant and aloof. Mary would try to laugh and reminisce and Molly would just not engage in a dialogue and was quick to make her exit. This really hurt Mary. Eventually, I lost track of Molly, but Mary (my childhood friend) and I became even closer.

Molly reappeared in my life and I still feel the same toward her. We are still great friends. However, she still seems cold toward my other friend, Mary. I am still great friends with Mary. I have no idea what happened so many years ago. But I feel caught in the middle.

What do you do when two people that you love….are on the outs with each other? (Well, actually Mary doesn’t not like Molly…she is still bewildered as to what happened.) Molly mentioned Mary briefly, but that was it. No mention again. So, I end up not talking about Mary to Molly and not talking about Molly to Mary. I don’t want either of their feelings to be hurt. I love them both dearly.

I just wish it was like the old days…the Three Musketeers again.

Any ideas? Has this ever happened to you? What did you do?