I have just come across this and it resonated with me. If I am having a rough day with old tapes playing and depression and anxiety levels ratcheting up, sometimes people will say to me "Well, aren't you glad you don't see them anymore?" as if I should have gotten over it when I went NC. (Four years and counting)
"Ambiguous loss" is a perfect descriptor.
https://onbeing.org/programs/pauline-boss-the-myth-of-closure-dec2018/
Thank you very much for sharing this. "Ambiguous loss" aptly describes how I feel about my divorce, particularly because my ex-husband is alive (I think) but has ghosted me and our daughters off and on for several years.
In T it was recommended I read a book called "Recovering from Losses in Life", a book devoted to ambiguous loss. We don't have any place to grieve these kinds of losses in our culture. I'm glad you're finding terminology and getting some clarity!