I have object constancy issues, too, more around therapists than other people in my life (hm, and a couple other male authority figures--though I did go through a separation anxiety phase around 12 when my mom had cancer, which she survived). I've been helped some by transitional objects, like with ex-marriage counselor, it was a particularly caring voicemail he left at one point that I would listen to if I needed comforting. I used to see ex-T in the same office as him, and I'd also find comfort in just seeing his car in the parking lot or his office door closed (meaning he was there and in session). Ex-T had seemed puzzled that I was comforted just seeing evidence of his being there.

With current T, I've had a few different stones from his office, which helped some (and also led to a huge conflict, but that's another story...). I wanted him to leave me voicemail (or just record a voice memo on my phone) when he was going out of town once or else (hand)write me a few words, but he never did. (He did write a couple words of encouragement for something else.) I wonder if he didn't want to because of the ex-MC one (which I'd told him about).

Some of my lack of object constancy will show up in outside contact between sessions (to current T, ex-MC, and ex-T). Where it's like I needed a reminder that they were there. Sometimes I literally have asked, "Just making sure you still exist," particularly if they were on vacation, we'd had a conflict, etc.

Current T is more of a "showing he cares" type rather than saying the words (and he's weird and very specific about how he's willing to phrase it for clients--something else that once led to a conflict!). A couple weeks ago, I said how I feel I have accepted that he cares due to his actions and (for the most part) consistency. But then I ended up emailing to say that I do still want the words on occasion, as I'm a words person. He ended up sending a very sweet (but still within his boundaries) email back, talking about things like "I care a great deal about your well-being" (his boundary is not saying the phrase "I care about you") and other things beyond what I'd have expected (like about my being a good person and his having compassion for my struggles).

I'd said in the email asking for that how I wouldn't need him to say it all the time, just on occasion. I feel now like the email is something I can look at when I have doubts that he cares (without having to reach out to him). I was thinking about it, and I am doing better with object constancy (and insecure/anxious attachment) lately, but that I do still need reminders at times for when the doubt creeps in.

I think it's a long process to work through, like most anything that likely has roots in childhood. And I agree on the comment of it coming from inconsistent parenting, or parents who didn't meet one's needs in some way (like emotional needs or otherwise). Or dealing with some sort of abandonment at a young (or older) age.