Nothing at all, but that last line, "When is my turn to have fun?" Is a bit transactional, like there's an expectation and that's the problematic part.

The toxicity is the weird incel framing around the whole thing. It leans heavily into incel tropes about how women sleep around with physically attractive asshole men when younger and then look for a more stable "nice guy" men when older. The trope is that women will reproduce with asshole gym bro types and then seek relationships with nerds to obtain resources to raise the children they've given birth to. It's the classic cuckhold meme.

The "backup option" part is the toxic thing. It frames women as farm animals looking for a mate, rather than actual complex human beings with different desires and changing personalities through their whole lives. Aka, just like men. People change, and they want different things at different points in their life.

It's not that the woman in the story fucked a bunch of guys and then, as a last resort, settled for OP. I mean, just think of how absurd that idea is. It is literally not possible to run out of people to sleep with. They don't think OP is beneath them and have always felt that way, only settling for them now. Why would she need to? There's no shortage of other men out there if she thinks OP is beneath her.

Rather, people just want different things at different points in their lives. OP didn't tick that box years earlier, but now maybe he does. She wasn't attracted to him then, but she is now. The heart just works that way sometimes. There's no need to add a bunch of incel bullshit to what is easily explainable as the complexities of human emotion.

The reason this is so toxic is that it's applying this weird bizarre manipulative behavior to the woman in the story - aka parroting incel themes. It accuses her of this deliberate years-long plot, working through a long list of men she finds superior until finally settling for OP. This isn't how human beings actually behave. Instead, she just happened to not be attracted to OP before, but happens to be now. You don't need to go into it any deeper than that. People are complex and their hearts change.

This "backup option" framing is just really toxic and creepy.