What is up with that?

What is up with guys that don't put in the effort to be with you, but the moment you decide to let them go because you had enough, they come crawling back with "sweet nothings" promising to change and begging for another chance. And that cycle keeps repeating itself over and over again. Blocking does not help because they find another way of contacting you. It's been going on for years now and i seriously don't know what to do.. I'm only getting older, with no baby or husband.. and my 30yo eggs can't keep waiting on this. Fml right now.