Guys, Curious about actions?

I work with this guy at work and we flirt from time to time. He has a relationship and there was one time a few months ago we made out, and felt each other up. Otherwise nothing else has gone on, just the occasional flirting.
We had a work event and he brought her along and introduced her to some of the staff, but did not me. Now it didn’t matter that he didn’t, I didn’t say anything obviously, I wouldn’t do that. But I’m curious as to why since we do communicate at work.

Guys, Curious about actions?
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