I’d be less pissed off but just as hurt.
My current interest is a poly bi woman. The question is almost without meaning.
But I voted “less upset.”
Did I fuck you up so bad you are turning to me?
I admit, that would be my first thought. And yeah, I’d be pretty pissed he’d been lying to me all these years, especially since I share everything with him, even my darkest feelings and emotions, and am about as non-judgemental as you can get on sexuality.
I’d be pretty upset if my wife left me for another man. But if my wife left me for a woman, for a nontrivial interval of time, my head would be too busy exploding over the notion that my wife was at all sexually attracted to other women to get around to being upset over being left.
Um, that last word should be men, of course.
If I spent all day baking a pie for a pie contest and I lost, I’d be upset. If I spent all day baking a pie for what turned out to be a cake contest, I’d still be upset, but for a different reason. But in the end, I’d be like “Whaddaya gonna do. All I got is pie.” and it’d hurt less overall.
They make your gender’s ass less desirable to me? 
The word upset is in every response.
I couldn’t vote.
I thought it was supposed to be “turning me on.” I was trying to figure out what dirty, spanky game you had going on with tdn.
Thank you. I had no idea what you were saying. 
You weren’t invited. I think that’s grounds to be upset.
You wouldn’t be upset if an SO left you for someone else?
I voted straight/would be more upset, but that’s for one reason only: I am a child of the 80’s, and I would be VERY VERY PISSED if he had (potentially) exposed me to HIV while he was in the process of finding his true orientation. Part of that is because I have a friend who was orphaned that way at a young age - her dad was a closet case, slept with all sorts of boys on the side, and infected her mom.
I would also feel, very illogically, that there must be something very wrong about me, that I had somehow been such a horrible person that I’d driven him away not only from me but from my entire gender. Again, not logical, but there you go.
Take my wife…Please! 
Sorry. I just had to throw that one in the mix.
I voted less upset. Hell, if the other woman was hot enough I might even try to talk her into sharing. Otherwise another woman wouldn’t bother me as much as another man. It’s probably a genetic/traditional thing about not letting another man steal your woman.