Why would a guy im casual with try and make me jealous (when it was my decision to be casual)?

He will make comments like:
I have so many girls after me
Your only going to keep having sex with me then get rid of me.

I obviously never give him satisfaction I just ignore him but it’s starting to make me wonder why he’s acting like this.
Why would a guy im casual with try and make me jealous (when it was my decision to be casual)?
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