Medically, that's just reckless. Emotionally, if he IS having an affair, I think most men in that situation would view the sex as a sort of validation (or at least a "looking the other way") at their infidelity.
Puppy
I wish I could know for sure. Honestly, I don't see how he could be having a PA with as much time as he spends at home and/or with the kids. My guess has been EA for the most part. Maybe on the verge of PA when all this first came about. My first husband cheated on me and I think I have a pretty good gut instinct about these things. I would feel better if I could have a look at his cellphone records or email. I did hack into his Facebook page and went through all his messages a few weeks ago. I did not find any evidence of wrongdoing. Yeah - there were a few people I preferred he not be "friends" with, but no messages back and forth that would totally inappropriate.
The bad part is, I didn't even think in terms of medically, with sex! After 20 years you kinda get used to not thinking about that!
Guess it sounds like I am trying to rationalize in terms of what I want to think, I know. I will say that to me, an EA is no small matter even if not evolved into a PA!
