My bf has trouble keeping it hard during sex after getting hit in jujitsu last week? n e other guys have this?

He says its not my body n I believe him cuz he usually starts n wants sex yet he said its an effort to keep it hard n that he doesn't enjoy it. He just recently started jujitsu n that's all he ever talks About. Could it be that he's still excited over it and not horny with me or is it cuz he got hit there a lot last week?