Yes per my definition, maybe or probably per the standard definition. I say yes per my definition because I caught the "emotional" affair, which for me is much worse than physical. I don't really care if she'd want to be physical with someone else, though I wouldn't have liked it in this context.
Would have been like 6 years ago now. She was getting more distant. I had been really busy at work for a couple months, but when a nothing fight turned into "I might go to my parents for a couple days" I figured there had to be more at play than my work. She has an iPhone and was logged in on her iPad too, so her apple to apple texts synced to the iPad. I snooped and learned she had lied to me about one coworker inparticular being at the bar on several occasions she had gone out with colleagues (but could confirm she actually was "out", she just left this guy out as an attendee). I snooped through her phone to fill in some gaps for the non-Apple to Apple texts and called her out.
That coworker had actually been transferred to a different, but still close by, location some months prior. I told her I didn't want her talking to him outside of work reasons if they were in the same spot. She thought I'd snooped through her phone so had no clue on the iPad. I don't remember the timeline, maybe a couple weeks or a month, but soon they were texting again. It was too flirty for my liking but not overtly so where I'd be 100% they were fucking. Over the course of a couple weeks it became more and more frequent as we were further from our blowup when I called her out. It all kind of culminated when one day I watched, in real time, them make plans to meet up for an early happy hour at like 3 in the afternoon while she was telling me she was running around for work. I even called while I knew they were together and she stepped out to keep the lie up.
Once I called her out and basically put divorce on the table it ended. I genuinely believe that. She swore they were never physical and she was just enjoying the attention since we'd been together so long. Part of me believes that because it's difficult to know when they would have fucked, I could see she was actually at the bar when she said she was, her patterns didn't really change, etc. At the same time, a lot of effort for two adults to just be flirty. Oh well, at this point it doesn't matter and I've never been given a reason to snoop since.
Like I said, if she wants to fuck someone else she can. But I'd definitely prefer it not to be a coworker. I don't want my wife getting caught up in workplace gossip. She doesn't work anymore so moot point these days.