I love this book -- a standalone, with an established relationship, not a romance, no spice, no miscommunication or couple-drama ... just a MC with a lot on his plate, and a LI who backs him 100% and isn't trying to take over the plot.

The setting is a fantasy-Venice and is vividly described.  As in a lot of classic literature (though more literally than usual), the house is a character in its own right, which is a very niche trope to love but here we are.

The magic system, using official and unofficial demonic bargains, was fascinating and intricate, though not info-dumpily spelt out (so if you like more detail, be aware of that going in.)

Definitely recommended if you're interested in a 'slice-of-life' vibe, but also a plot with increasingly high stakes.