Same two things bother me, too Julie....he cheated on his ex-wife with this couple. I wonder if he ever confessed to his then wife and if it was before or after she joined in? and the behaviour of this couple is disconcerting.
The cheating issue in and of itself is very much worth some discussion, if it hasn't already.
The couple is another issue.
JC2you: Your b/f is saying all the right things a good partner needs to say in this situation. He is telling you a lot, and maybe more than the couple would think he would tell you? Which is a good thing - you two should know more about your lives and each other than any other person. What he's saying to you tells me that yes, he can walk away from these activities.
I think it's not uncommon when a single person (swinger or non) becomes involved in a serious relationship, for previous friends - singles or couples - to occasionally have some feelings of abandonment or jealousy over a perceived loss of the single friend. The single is now becoming a couple, and not everyone adapts well to the change.
Minimally, this couple isn't respecting your relationship with your b/f, and their behaviour isn't respectful of him or his choices either.
It sounds like your b/f hasn't had a 'talk' with them about their sexual activities with him or the both of you, and further, they aren't asking for the information, something any responsible couple would find out first, especially when their friend, your b/f, is obviously in a new relationship.
You two need to make decisions based on what is best for you, and the b/f needs to convey to this couple what that decision is. No need to explain the 'why'...it's really none of their business nor do they have a right to know. They obviously aren't supportive of your relationship, so I'd suggest keep them at arm's length, at least for a while.
I apologize if this posting reads a bit disjointed...I have people walking back and forth behind me here
I hope this is helpful to you