Hmm good question. Was discussintgxT stuff with T last session, and I did wonder why I still miss her (after more than a year!!) when relationship w current T works pretty similar to what I initially hoped to develop w xT. Might be interesting to put it in this broader context.

BTW, for me part of the answer is transference stuff. Despite cognitively understanding that she ****ed up and failed me as a T, some stupid stuck-in-childhood part of my brain insists that she's the most wonderful being to ever have walked on Earth, and everything would have been perfect if only I tried harder or did/said the right things, and is there really nothing more I can try? As explained to me by a number of Ts and articles, children desperately need to see their parents as 'good' and try at all costs preserve that positive image in their minds (e.g blaming themselves), so I think if parental transference is at play, then it might trigger this 'defence mechanism' even if your actual childhood was as non-abusive as it can get.

Then there's the 'must find the good in everything' coping mechanism, which can gradually shift from 'this really sucks but at least something good came out of it' to 'it's for the better, might suck a little, but nothing is perfect'

But also the process of coping with their **** takes up a lot of mental resources, and ... it's a connection, a sort of intimacy, a sort of challenge, probably a lot of other things that might be hard to let go and leave a void. Perhaps it!s a bit of Sunk Cost Fallacy - part of the brain says 'I invested so much into trusting this person, putting up with her quirks, trying to fix things, there has to be a way to make it pay off somehow', when the ratioal part already decided to cut my losses and move on.