He stopped messaging me after sex

So we've been talking for over a month now, everything was fine. He said he wasn't looking for a hook up which is the same for me.

We eventually had sex after a few weeks of talking, he stayed at mine for a few days and we had sex every day.

But each time he only lasted 2 minutes max. The first time wasn't even 10 seconds. All in all the sex was bad, but I looked past it because I was genuinely interested in him.

But a week after that he kind of replied less and less. Eventually stopped talking to me. Why is this? Is it because of the sex? Now I feel kinda used for sex but I don't know how I feel about this. Is it because he's embarrassed or I don't know what.

He did say he would be keen to hang out again but I don't know if he meant it.