An ex lover of many yrs keeps on contact. Have sexual conversations all the time for yrs. Even gets jealous when you talk about the guy you are currently seeing. Man who keeps intimate conversations with a woman he has had sex with but lives to far. When he comes to town he text the woman but don’t make any effort to see her.
I just got out of a relationship with a narcissist so from my experience, another reason would be that if that person is a narc then the ex’es give them a supply source for ego stroking and a way to make the current partner jealous and more submissive (triangulation). You would see other narc symptoms if that is the case, such as blame shifting, gas lighting, self-absorbed, never thinking they are wrong, etc… anyway, just another possibility..