there could be a lot of other things going on here, but my inclination is that now he's wondering where he fits in with your past

hell I'm almost 35 with a plentiful, successful sexual history and this shit still happens to me. I'm confident in what I do with great results and I still suffer from intrusive insecure thoughts

if this is the case, he's going to need assurance, and probably lots of willing practice from his partner

if something else is going on here like many others have mentioned, then you're guess is as good as ours here. you know him better than any of us

is it normal for him to clam up when communicating about things? again my guess is that there is a massive amount of pressure in regards to sex and performance that I can almost guarantee he's suffering from right now