The article (link below) really helped me understand trauma bonding in a new way. It explains why it is so hard to let go of toxic relationships. I have been out of said toxic relationship for almost 20 years and have been no contact with my ex from this relationship for about half of that. I was still struggling with intrusive thoughts about him and our relationship. This article helped me a ton. It explains why it is harder to let go of these kinds of relationships as opposed to healthy relationships.
https://tealswan.com/resources/articles/why-you-cant-leave-the-relationship-intermittent-reinforcement-r210/
https://tealswan.com/resources/articles/why-you-cant-leave-the-relationship-intermittent-reinforcement-r210/