Why would he say that. it hurt my feelings?

It’s a guy I’m messing with I haven’t slept with him for a month but he’s the only guy I’ve been sleeping with. We finally slept together today and when I got home he called me and said he know I’ve been having sex I said I haven’t and it’s true I haven’t but he’s saying I have because I feel different. It hurted when he said that so I blocked him. I really didn’t like what he said because I literally try my best to see him and do what I can and he still always find something wrong.
Why would he say that. it hurt my feelings?
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