If you want to know if this book has infidelity before picking it up:

it doesn't

When I started this, I was worried it would either be too much like the first book. It is, in some ways—there are political machinations, murders, and two characters who find themselves in a relationship but still haven't figured out how to navigate it. But it was different enough that I had a good time reading.

Considering where we left Cae and Vel, it makes sense that the story focuses on dealing with trauma and grief, and what that can do to a relationship. Cae has lost two family members within a short period, and clings harder to Vel because he feels he has nobody left. Vel is still working through his own ordeals, as well as the guilt of being the reason behind said deaths. Cae doesn't blame him, but that distinction doesn't matter to his spiraling brain.

I will admit that I got frustrated with both of them after a certain point. Their relationship isn't smooth sailing by any means, but a lot of it could be avoided with clear communication from one of them. Instead, they continue to willfully misunderstand each other. And the thing is, their relationship is facing real difficulties. But somehow, by the end, Vel realizes he does love Cae, and suddenly all the problems just went away. There was no more mention of uncertainty or communicating, because being in love fixed everything. I wish the author had handled that differently, but I still enjoyed the rest of the story.