Why do men avoid or ghost girls after sex with them?

In my situation we have known each other years through work, the past year or two things have a look at been relationship like without anything physical. Things slowly started progressing the past few months until 4 weeks ago we slept together, it was planned but after we both admitted it was a long time coming. He’s always said he cared for me, and I genuinly felt that to be true. We would speak daily and meet often, hold hands, cuddle. But since sleeping together he’s completely ignored me, or been blunt with replies if any. I actually feel physically sick inside, that he would do this. What would be the reason, I understand men use girls for sex, but he could have used anyone why someone he was close too? Surely he’s got to miss me, I was part of his life for years he can’t just forget I exist. Could it be the sex was bad, I mean I thought it was good but you never know.

Updates
1 y
Just an update. He actually texted me this morning, a stupid comment like “are you alive?” Anyway I have mo opened it and I’m leaving him to sweat a few days!
Why do men avoid or ghost girls after sex with them?
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