I've got this whole note file on my phone where I keep titles that reliably pull me out of a funk. The top of that list for pure, fizzy fun is 'The Love Hypothesis' by Ali Hazelwood. It nails the fake-dating trope with STEM academia as a backdrop, and the humor comes from the lead character's internal overthinking as much as the situational comedy. It’s smart without being mean, and the romance feels earned.
For something with a slightly more chaotic, found-family energy, I'd point you toward 'Boyfriend Material' by Alexis Hall. The premise of a fake boyfriend for PR reasons is classic, but the execution is all awkward British charm and escalating disasters. The protagonist's inner monologue is a masterclass in self-deprecating humor that somehow never gets tiresome. It’s less about big slapstick moments and more about the cringe-humor of two people trying to navigate a ridiculous arrangement.
If you're open to a paranormal twist, 'Not the Witch You Wed' by April Asher is a delight. A witch and a werewolf-alpha forced into a fake engagement for political reasons? Yes, please. The comedy stems from magical mishaps and the sheer stubbornness of the leads, and it never takes itself too seriously. It’s the book equivalent of a warm, slightly magical hug with a side of laughter. My only gripe is that the sequel didn't quite capture the same spark for me, but the first one is pure gold.