Tropes:

opposites attract, single parent

Steam level: 🌶

I had a good time with this. My nerdy little heart really appreciated the setup of people getting matched up based on their DNA. The side characters were all stand-outs as well.

This does fall into the pitfall of the male love interest being described as basically perfect once the romance gets going, completely ignoring the way he acted initially. He has one moment where he acknowledges he was being an ass, although even that kind of gets explained away as him being shy.

The conflict is external instead of an issue in the relationship, and it took the story in a direction I wasn't expecting. I really appreciated the way Jess handled the communication: she tells River that something is bothering her, and right after acknowledges that she's sure he'll feel stressed about what it is until they get the chance to talk, and that she's sorry about that. It was a minor moment, but I liked what that said about their communication in general.

With regards to the ending:

I wasn't fully satisfied with it. The book is clearly insinuating that, even after re-running the test on their DNA, they are still a diamond match. Which means that the narrative never deals with how River bailed on the relationship when there was reason to suspect they weren't a diamond match, and only came back after learning they were. Jess accuses him of needing to know their score before choosing her, which he denies, but it's hard to believe considering the timing of everything. I kind of wish he had chosen to not look at the score until after he'd reconciled with Jess.