Fleishman Is In Trouble by Taffy Brodesser-Akner

I don't know how I missed this book. So clever and sad and funny but also heartbreaking in big and small ways. A huge achievement, Toby Fleishman is a hero, but also incredibly normal.

From the back

Finally free from his nightmare marriage, Toby Fleishman is ready for a life of online dating and weekend-only parental duties. But as he optimistically looks to a future that is wildly different from the one he imagined, his life turns upside-down as his ex-wife, Rachel, suddenly disappears.

While Toby tries to find out what happened - juggling work, kids and his new, app-assisted sexual popularity - his tidy narrative of a spurned husband is his sole consolation. But if he ever wants to really understand where Rachel went and what really happened to his marriage, he is going to have to consider that he might not have seen it all that clearly in the first place . . .