Ex coming back to check up on you

I don’t understand when men come to your life after months of no contact Just to check in. What do they mean by this. Not to apologize or to fix things just checking in. Can somebody explain it to me. Like why men do that ? Just to make sure we don’t forget their existence. Why can’t they leave them alone if they’re not willing to do anything anyway. My ex did this some time before. He’s older than me he’s 29 and I thought for a second he had something to say but nothing really