First, you clearly care a lot about your boyfriend’s happiness and emotional security, and I think that’s awesome. I’m sure the hurt for him is real, regardless of whether it’s rational.

That said, this is a pretty common thing for couples to comment on. I don’t think you missed any social cues due to ASD in this instance, most people wouldn’t think this is a big transgression, if a transgression at all. It’s one thing to say you think someone you actually know is hot, that could justifiably lead to some insecurity. Talking about celebrity crushes just isn’t the same. My wife and I are totally monogamous, but it doesn’t bother me hearing her drool over Henry Cavill, and she doesn’t mind me drooling over Christina Ricci. It’s just silly crush stuff, not real.

I hope he can get some help with this and work through it.