I want to add that I don't think getting bottles of wine to loosen him up to talk is the good way to go here. If the only way he can feel comfortable talking is when he's not sober, that's a problem that you probably don't want to enable, especially if you have any interest in a solid relationship with good communication and with him learning how to communicate.
Probably -- from what I can tell in all this -- the best bet is for him to just seek out a general therapist. It sounds like these issues happening in sex are also happening outside of it, so while they are manifesting a lot in sex per your notice, they are likely bigger than that. (Plus, sex therapy tends to be harder to get covered by insurance, and there are far fewer sex therapists, so finding one can be a lot harder.) I'd suggest he instead work on seeking out a general therapist and just be very clear in screening appointments about the issues he's having to find that right person. I don't know what all his stuff is, obviously, and from the sounds of things, you don't either, so it will be on him to be honest with therapists about that.
If it turns out therapists think that a sex therapist is the right bet for him, they'll let him know that.
Too, if therapy is something within reach for you, I'd also add that you might find having your own therapist is helpful with some of the challenges you're experiencing in this relationship. And if you're the kind of person inclined to get hyper-focused on helping a partner with all their stuff (I am myself very familiar with this problem!), having your own therapist can also help you be sure you are focusing on your own needs and issues, including anything that might be at play with any of this on your end.
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. - Margaret Mead