So, would the thought be almost like doing couples counseling but with friends? Or for the T to ask your friend what kind of friend they think you are? Just trying to figure out the idea here.

My T has helped me with learning how other people might respond to me and how to communicate better with them, but without actually meeting any of the other people. Like if I share, for example, how a friend reacted to something I told her, he might share a couple reasons why she could have responded that way, what could have been going on in her head (while admitting that he didn't know). Some of it has been difficult (especially when he shares his reactions to things I say to him--like his personal reactions), but I've also learned quite a bit, and it's helped me in outside relationships. I think the biggest thing has been learning that many (probably most) people's minds don't work like mind does, so what I might want/expect from them might be different from what they want/expect from me. Stuff like that.

Not sure how much sense I'm making--only partway through my coffee! I guess I'm wondering how much you've explored that sort of thing with your T. If you have, and you've hit a dead end regarding the friendship stuff, then I think it could be worth trying to bring in a friend. You'd just need to be prepared for him or her potentially saying some things that could upset you.