What does that mean?

It's a bit weird situation (at least for me). There's one guy with who I had long distance relationship. We stopped it on his own initiative (September 2016). OK, that's not a problem. People always come and go. Moreover, he is not the first and not the last guy in my life. In January I got a friend request on Facebook from him. So, I accepted. A few days ago he started following me on Instagram. In my opinion, if you leave - don't come back forever (I know, it sounds cruel). What do you think about all this?

You said it yourself - In your opinion. Just because you have this rule that you never want to speak with other people again after the first bump in the road does not mean that everyone else sees it that way. I have no idea why the guy is following you, why he stopped talking to you in the first place or whether he is worth trying to talk to again. I'm not even sure if he wants to try dating again, since he could just not want to kick you out of his life and still be friends with you. But it is a little weird if he has never tried to contact you again in all of this time and just followed you and added you - did you let him talk to you? Will say that long-distance anything rarely works. But I would maybe talk to the guy, see why he is still keeping a line of contact with you, and decide if you really do believe all ties must be severed.