1) The parents are absolutely terrible. The father is so ridiculously absent it's not even funny. The mother gets better at the end but for most of the book she's pretty much a total asshole. Several of Zennie's friends are assholes too.
2) Ali's relationship with Daniel goes pretty fast. I think it would have been better without that ending. Daniel was also pretty bland. He was likable, a good guy after his jerk brother, but he didn't seem to have any negative traits whatsoever, and that makes for a boring character. I was honestly hoping to hear something negative about him. I would have even taken messiness. Instead he was an angel. Not bad, just not realistic.
I did appreciate Ali learning to see her worth, but I wish that wasn't because of Daniel.
3) Have you even seen/heard the musical The Last Five Years? I had the same complicated feelings on that as I do for Nigel and Finola's relationship. Sure, Finola wasn't perfect but should she really accept blame for her husband's cheating? If he was unhappy, why didn't he say something? If he wasn't getting what he wanted, why didn't he leave? I have such a hard time sympathizing with cheaters. I know the author's going for realistic and marriages are more complicated than that... but Nigel cheats on her with a younger woman known for getting with married men, blindsides her, and honestly handles her understandably bad reaction with poor grace, and I'm supposed to feel badly for him?
Although Finola accepts some blame--and possibly deserves some--none of the book is told from Nigel's point of view, so it's kind of hard for me to understand. This might have been a better plot if it was in its own book and had dual perspectives from both of them. I think that could make an interesting dramatic book. As it was, my disinclination to sympathize with cheaters and a lack of understanding on what made Nigel cheats pretty much cheapens this plot a little. The whole book is basically Finola learning that she's kind of selfish and needs to be better, but so much of her plot revolves her around feeling terrible after her husband leaves, so I'm a little torn on that.
4) People's reactions to Zennie being a surrogate for her friends were... off? Like I'm sure these are two totally realistic to have, but people were very rude about it. Look, Zennie is an adult. Lots of people are surrogates. Lots of people have babies for friends. Sometimes it doesn't work out. That doesn't mean you need to be rude about it. Also, it's already happened. Get over it.
5) I was really hoping Zennie would be asexual or aromantic. She seems set up to be like that, but in the end she ends up with someone anyway. Whatever, I'm still thinking she's demi or something, but the author really doesn't handle this well. Also, while I think her mother setting her up with a lesbian was supposed to be well-meaning, and I'm glad they became friends, this sort of thing is weirdly out of place in modern media. Zennie's ex asks her if she's a lesbian in kind of an offensive way (to me), and her mother assumes she must be a lesbian because she's not in a long-time relationship. Zennie can't be one with herself apparently; there has to be something "wrong" with her. It's kind of a messy plot line and I hated it and it did knock down my enjoyment some.