Interestingly I talked with my therapist about the omnipresent emotional connection I have with the memory of my relationship despite the rational part of me knowing her departure was for the best (
https://bpdfamily.com/message_board/index.php?topic=232987.0).
She is a CBT therapist and said that, first, trying to block the experience out of your mind is ineffective.
She suggested two tools to confront these thoughts (She quoted some literature used for war veterans), and one of them was to write about the details of the relationship. Obviously this forum largely fills this to some extent, but she suggested a prolonged and detailed account of the relationship. With the details, the highs, lows, and the banalities as well are included in the narrative. It is cathartic to express these thoughts in writing, but it also doesn't allow us to bias our thoughts on just the wonderful things we were addicted to. It is just a narrative on a relationship with all its warts.
The other tool was to introduce and explore new experiences (learn a new language, learn to draw, re-build that 67 VW bug, etc) that occupy our present thoughts and gradually push the memory of our relationship further and further into the margins of our consciousness.
I hope this helps.