Nagging Thoughts

I hate the lingering thought of her still messaging him after all this time. And the fact that he still replies. I'm trying to understand why, so that these thoughts would stop nagging me. I should be contented with the thought that he severed everything. But still having contact with her isn't really severing everything at all. Or is it? I trust that they don't go out anymore but why is she still after him? What we have isn't perfect, he isn't perfect, I'm not perfect. He is a guy and he can't help it if there's someone throwing herself at him. I just wish he'd cut off everything..block her..tell her to stop because he has someone he loves and he's happy. Or is he? Damn insecurities. All I can do is wait and see how this goes. Only time can tell.