DP, as others pointed out (and you have acknowledged several times), your relationship with your T was not a therapeutic one. Perhaps because it was more... jovial, less deep, it is easier for him to separate.

I have had decent friendships with coworkers - people I have confided in and cried in front of - and then, when I moved jobs, those people just... stopped talking to me. Not out of malice, that I can tell - and we had emotional(-ish) goodbyes - but just... we don't talk anymore. They don't initiate contact and honestly I don't either. It doesn't bother me though, because we didn't have a deep connection beyond the office. I'm not at that office anymore. It's more... a change in the daily routine. *shrug* Maybe that's your T's perspective? Not a therapeutic approach, but an explanation nonetheless.