Okay, so you want Cupid books for YA that actually dig into the mythology, not just use the name as a cute romance trope. That’s a bit tricky because a lot of them just borrow the concept for a love-at-first-sight plot.
For straight-up mythology retellings, you can’t go wrong with 'The Dark Wife' by Sarah Diemer, though that’s more Persephone/Hades. For Cupid specifically, 'Cupid: A Tale of Love and Desire' by Julius Lester is a fantastic, witty, and surprisingly deep dive into the original myth, but it’s more adult-leaning and might not be marketed as YA, though a mature teen could totally handle it.
In the YA space, 'Goddess of Love' by P.C. Cast reimagines Venus and Cupid in a modern setting—it’s fun but focuses more on the goddess. The 'Starcrossed' series by Josephine Angelini tangentially involves Greek gods and has Eros/Cupid figures, but he’s not the central focus.
Honestly, the search modifier that worked for me was 'Eros myth YA retelling' rather than 'Cupid books.' It filters out the fluff and gets you closer to stories that grapple with the god’s chaotic, often dangerous power over desire, which is way more interesting than a simple matchmaker angle.