I sure wouldn't force them to take sides and would avoid talking about the R with them. I would just try to enjoy them without bringing them into the situation. If they ask, thank them for their concern and say as little as you feel like you can get away with without being rude. On the other hand, if your H is confiding in them and they want your side of the story, it sure would be tempting to fill them in. Honestly, I don't know. I guess it partly depends on how close you are with these friends.
