Why does this guy keep sending me memes?

So there is a guy that I have a bit of a history with. We were friends and then we kind of moved into a phase of a bit more than friends. We didn't talk for a while, but when I don't contact him as much, he will always reach out. He sends me lots of memes though. A lot of them have to do with inside jokes that we've shared over the life of our friendship. We will talk for a few days and then he will go cold again. Or communication slows down. Mind you, I'm not responding immediately. I have a life and it takes a while sometimes. He wilm then send me memes and short messages, and when I respond, he reads them and waits like at least 12 hours to respond. What the hell? I asked him if he needed something, be he wouldn't say, just that he hadn't heard from me in a while. He's always the one that ceases communication.
Why does this guy keep sending me memes?
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