Maybe I am confused or missing a piece. But why does him being poly mean you have to like women? There are ways to make it work without having to be "friends" with his secondary.
My concern would be, and this is from experience of knowing a lot of women, I hope you aren't walking into interations with women bitter and angry, which will never help your case of being friendly with them
My default setting is to just go with the flow, defer to others and walk on eggshells no matter if it makes me uncomfortable or not. My husband has encouraged me to become a stronger person, he is not against me learning who I am and what I like; although I can tell it hurts him that I am not on the same page.....at least right now.
Same page is a funny term, I don't think I have ever been on the same page with anyone. I just hope we are in the same damn chapter...haha
Afterall, she wouldn't have any REAL reason to stay and put up with me. Plus, if she and my husband find they get along too well, they both might bolt.
Assuming he finds this woman and they fall in love together, thats a damn good reason for her to stay and understand you. Regardless of the relationship configuration.
Lastly, I think you are more normal than you think. People in general throw around the friendship word very easily, maybe you need to rethink your general view on how you interact with people. I have a large social circle...mostly females...there almost needs to be a term between acquaintance and friend...if there is a descriptive ranking system. Every person, and how I open up to them is individual.
...Try not to paint broad strokes and enjoy the interactions, thats half the fun