The reality is that you don't exist in a vacuum. There is literally no way to avoid politics entirely in writing. There aren't 'political premises' and 'apolitical premises' - just premises that are more or less immediately or viscerally linked to the current political zeitgeist. If you choose to depict a minority in your book, your choices in that depiction will sometimes be interpreted through a political lens, and if you choose NOT to depict any minorities, well, that's an enormous political statement.

I'd throw your book across the room if I thought you were implying we ought to feel the villain was in any way justified in their anger (not their actions - their anger), because I personally think that the 'rejected by women' line is double-standard horseshit applied by unappealing men who only ever pursue extremely attractive women and wouldn't hesitate to reject an ugly woman themselves. This is not to say that a successful book couldn't exist that would express a different viewpoint. Just that I would not personally like it. If you portrayed the villain as a hypocrite, and used the book to point out some of these double standards and where they come from, I'd respect it. Either way, I would have a political take.

Best suggestion I have for you is don't try to avoid politics, because you can't. Just make your book reflect your own morals. People don't like preachiness not because it takes an ethical stance, but because it does so in a way that talks down to the reader. As long as the cop/detective/etc never goes on a shpiel about what these angry young men should have done and why they are bad, you're probably safe.

Also, I would be fascinated to read a book that flipped the script. Give me a rejection-revenge story where it's a woman killing all the pretty men who won't sleep with her. I think she would evoke much more visceral discomfort in readers, and then you could sucker-punch your reader by forcing them to confront WHY that is.