I dont know. Mine kept me pretty segregated from her friends in our 16 months. My take is, keep to the high road, dont over explain if asked and just let it roll on its course.
Mine segregated me more and more from his too. We have no real mutual friends. He never wanted to hang out with my friends or family. Well, one time but that was about 30 minutes for quick drinks. It had to be all about him and what he wanted all the time.
Rapror, how important are those mutual friends really to you? Is it such a big loss? I don't understand why these friends can't see the pattern, but this is true of many personality disordered types. People don't see. I've seen this before and it remains a big mystery to me too.