Ex keeps blocking me then unblocking me from fb.

So my ex and I have been over for almost a year now, we aren't friends on Facebook, and we have no communication from each other once so ever.

So why does he block me then unblock me on fb about every 3 months, even when we don't talk?

A little background, this guy is 35.
Ex keeps blocking me then unblocking me from fb.
Post Opinion