Flirting

We hooked up and now he's ignoring me?

There's this guy in my dorm who I know is kind of a ladies man. We have separate groups of friends but I kept running into him/passing by him and we'd say hi and eventually started having little conversations. Then he started calling out to me when he saw me and would go out of his way to come talk to me. Eventually he asked me to hang out so we went to a party together, but we just talked and nothing else happened. A couple days after that he asked me to hang out in his room and we hooked up.

That was like 3 weeks ago. He's stopped coming to talk to me when he sees me. I texted him twice a couple weeks ago: once inviting him to a party with me and once just to chat and he didn't respond to either. It's clear he's not interested anymore but what happened? It's one thing to meet a random girl, hook up and then not talk to her again but it's different to take the time to get to know her gradually and then just start ignoring her after hooking up.

Was he worried I would get attached or was I just a challenge and now he's moved on? Something else I'm missing?
We hooked up and now he's ignoring me?
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