Why did his face, get extremely red after we had sex?

So long story very short. I hooked up with this one dude, on the 20th of May of this past month. And I notice when he was having a big (O) he got a bit LOUD, lol smh. But anyways, after he got off and I looked at him. His face was like all red and crap. And I told him, and said look in the mirror. And the crazy thing is. Him and I are on the more darker side with skin tone. But he's a bit darker then me. Or has a more darker brown tone. And the simple fact that his face was able to show that much redness was crazy. Like he didn't believe me until I told him to look in the mirror. So my question is. Could he been embarrassed about how loud he was moaning, or other?
Why did his face, get extremely red after we had sex?
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