Oh (((fraeuken))))
I really feel bad for you, and totally "get" how it does not seem this could be possible, when you have met his family, and everything!
Please know, reading your first post the other day gave me some 25-years-late insight into a similar relationship I'd had, where I never got any sense of closure after he suddenly "ghosted" me. Thank you for sharing this, it has helped me to get that closure!
After I realized it was apparently "over," I'd sent his mother a thank-you card for her graciousness to me during the several months we dated and his family had gotten so thoroughly involved in "my life." My own mother had just died the previous year. She was such a lovely person.
And even his teen children had seemed enthusiastic about "us." (I was 42 at the time, and am now 66 years old.)
When he disappeared, somebody who knew me before I met him, laughed my pain off by saying "Oh, you didn't know he was the biggest bed-hopper in this county?" I was like "WHAT?" That is when I found out he had a well-earned reputation for charming and cheating rich girls. (I guess he found out I wasn't a rich girl, I worked for a living!)
But what really messed with my head for a long time afterwards, was that neither his family nor any of his friends had ever given me any clue that I was just his next "date." They made it all seem so "real," as in, "Finally he meets a good woman!" Ouch.
So, your post just seemed to confirm for me that this is more about them, than it is about us!
I, too, sought counseling after this, even though I had been through all kinds of trauma/drama long before I met him. It was sort of like the final straw for me, and I was really confused, like you sound.
P.S. I heard that a few months after our last communication, he stopped by where I used to work, (he had been introduced to all those folks, too) to ask after me. He tried to explain to a coworker friend of mine, who remembered him fondly, how it was that "we kinda cooled it a bit." Ha. Right. I think he was doing this same thing your guy was doing, but he never had the courage to call me again, either.
Over the many, many years since that time, I have bumped into him by accident here in our small community. He never did remarry, but has hung on to one woman or another for years at a time. He has never been able to meet my eyes or speak to me, since. How strange. I still cannot figure out what makes people act like that.
But please know, that this has little to nothing to do with you, and everything to do with who he really is. You were shielded from seeing that, by his design. Perhaps, to their family, that person is already known to be a serial relationship type, so I think they take the position they'll have no investment in how things turn out. And we may mistake their polite enthusiasm about us, for a real welcome.
But it doesn't make it hurt any less. So sorry!