Book request: it must include a scene where FMC’s significant other (MMC or not) is clearly falling for another woman in front of her and she has a crushed sort of acceptance

So as the title says, I’m looking for books with a specific scene in them.

I want FMC to be out with her significant other and come to the realization that he’s into another woman in front of her. Ideally nothing sexual, just the guy making moon eyes at a woman or doing special things for her that he doesn’t do for FMC. And I want FMC to then feel absolutely destroyed while at the same time kind of having a “nothing I can do, he’s clearly into her over me” sort of acceptance. Like quiet despair.

I picture this as with another man before she meets/gets with MMC, but I’m also open to second chance romances where we see MMC walk away from FMC the first time like this.

Honestly, whatever interpretation you feel fits!

Please no bullying, otherwise everything else is okay. I also like RH, so doesn’t have to just be one MMC