He does, but somehow his romance with Sidonie just wasn't all that for me. They're both okay characters, maybe it's just the way they fall in love so suddenly and completely that bothers me a bit.

Yeah, it's a play. Euripides wrote a play called Hippolytus with Phaedra/Phèdre as the female lead, then Seneca wrote one with her in the title role (Phaedra), and then in the seventeenth century Racine wrote his, based on those two. I've only read the last one, but I'm guessing it's the most accessible for a modern reader. The plot of all three plays is about her having feelings for her stepson Hippolytus, with all the disastrous consequences that entails. Supposedly Racine is the most balanced (or the least misogynistic if you want to put it that way) about it.