DP had an EA 3 years ago with a woman very different to myself.
He confessed, and everything has been ok since then. We have been together 4 years so the EA was soon into the start of our relationship.
Coincidentally, I happened to be in the same place as DP (he didn't know I was there), when he ran into her. They clearly hadn't seen or spoken to each other in a while. He didn't have to stop and talk to her, but he did. All this sounds reasonable, I guess they have no reason to not be civil to each other and given they work together I would expect that.
What irks me is that I managed to hear/lip read his parting words to her, and they were something along the lines of 'you look good/well'.
AIBU to be majorly pissed off by this?