I haven't read your backstory (yet), but I can relate for sure.
I wish I had an answer to why....I really don't know. If I had to take a guess, and really, I'm just thinking of my own sitch, it'd be that they like both worlds. They like the forever love we provide, the stability, the family, the history, etc....but they like the excitement, and new love feeling, and the absence of real life issues they get with the A partner.
Ultimately the cycling my XW was doing with me made me decide to go NC...it's healthier for me to have a stable life rather than the circle jerk she tries to run me thru. Sounds like you may be in a place where the contact is emotionally unhealthy for you as well....something to think about.
