Why did he look like he was going to cry after we had sex?

just a couple days ago my friend with benefits and i talked about all the positions we wanted to try while we were having sex. he made a huge groan and came during the first position....a few seconds later i noticed he was staring at the floor with a depressed/embarrassed look on his face like he was going to cry. when i tried asking what was wrong, he told me he's "out of shape" (sexually) so i kissed him passionately on the cheek & told him i still really enjoyed it. he kinda snapped at me... what was going on? will he want to have sex again? thank you!!