Why do exes come back after ghosting you with no explanation?

Weird things have happened to me where someone will stop talking to me for no apparent reason other than that they want to move on. Then they go no contact for say a year or two and try to come back with no explanation why. They say they just wanted to say hi or whatever but then they were not civil about it before. Usually i block these guys and never welcome them back since they had put me in the back burner for so long.

Why do exes come back after ghosting you with no explanation?
Post Opinion