Why would he block me on fb and instagram but not Snapchat?

Anonymous
My ex and I had what I thought was a great relationship. Maybe moved a bit fast but I thought we were happy. He became distant the last few weeks and broke up with me 3 days before Thanksgiving. His reasons to which I believed at the time turned out to be a complete lie. He said he would be moving away in a few months time and thought it would be better to end it now before things kept getting better between us. He cried, told me I’m only the second person he’s ever loved and only person he really cares about and this is the hardest thing he’s done in his life. He said he would feel guilty if I moved for him. Well turns out he isn’t even moving. He had dinner with me a week later that was his idea and his idea to tell me to wait to get my stuff until we had this dinner. During this time he told me the same lies but tried to act caring.
He a few weeks later started seeing this random woman. Few weeks after that they are in a Facebook official relationship. At this time he unfriended me and my close friends on Facebook. He blocked us on Instagram. About a month or so ago he actually blocked me on Facebook. He also deleted every picture of us and untagged himself in everything associated with me.
Him and his new girlfriend broke up a few weeks ago after like two months together. He still to this day watches all my Snapchats after I unfriended him.
Why does he follow me on there but blocked me on the other ones? It actually kind of hurts cause I still love him and it sucks watching someone cut you out of their life like that. do you think he will ever reach out to me?
He used to follow me on twitter until I blocked him on there cause he was liking tweets and then unliking them hours later.

I miss him so much and I don’t even know why. He was married before me and claims she cheated on him. So basically he was married 4 years, met me after 4 months and we dated for 5 months. Then got with that girl who knows how soon after we broke up and then they lasted a couple months
Why would he block me on fb and instagram but not Snapchat?
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