Alain de Botton has spent thirty years arguing that philosophy should help you with the actual problems of an actual Tuesday: work, anxiety, and above all, love. His School of Life project published reading lists for each of those problems. This is the love list, all ten books, with my notes on what each one is actually like to read.
A warning before the list. Most books about love are advice. Almost none of these are. They are novels, essays and one Platonic dinner party, and they work on you sideways.
Who is Alain de Botton?
Born in Zurich in 1969, educated at Cambridge, with a Masters in philosophy from King's College London. His books, The Consolations of Philosophy and The Art of Travel among them, take serious ideas and put them to work on ordinary life. Some academics sniff at him for exactly this. I think it's the hardest kind of writing there is.

The list

The original doomed-love novel, and the reason half of Europe's young men spent the 1770s in yellow trousers feeling sorry for themselves. Read it to see obsessive first love from the inside, written before psychology had a name for any of it. It does not end well, and that is rather the point.

Stendhal dissects falling in love like a scientist who is also a hopeless romantic, which is exactly what he was. His theory of "crystallisation", the process by which we coat an ordinary person in imagined perfections, explains more bad decisions than any book I know.

Armstrong's central claim is that love is a skill rather than a feeling that happens to you. If that's true, it can be practised and improved. The most quietly Stoic book on the list.

De Botton's own first book: one relationship, from the seat numbers on the flight where they met to the aftermath, with philosophical commentary running alongside. Funnier than it has any right to be, and painfully accurate about the gap between hope and self-knowledge.

Fragments of a lover's inner monologue: the waiting, the jealousy, the rereading of one text message. The hardest read here, and the one that most feels like being inside the thing itself.

Emma Bovary wrecks her life chasing the love she read about in novels. Flaubert's warning is uncomfortable in the age of romantic comedies and other people's highlight reels: the fantasy is the enemy of the marriage.

Fromm argues that love is an art demanding discipline and practice, like music or carpentry. Sixty pages in, you stop asking "how do I find the right person?" and start asking "how would I become the right person?" That swap is worth the cover price.

A dinner party where each guest gives a speech about love, including Aristophanes' famous image of humans as split halves searching for each other. 2,400 years old and still the deepest thing on this list.

Zeldin traces how private life, conversation and affection have changed across centuries. The wide-angle lens: love as something humanity is still learning.

The one practical manual on the list, built on attachment theory. If you want research and exercises rather than literature, start here.
Where I'd start
If you would rather have the compressed version, I collected fifty of his sharpest one-liners.
If you read one: Fromm. If you read two: Fromm, then Essays in Love. The rest can arrive as your relationship raises the relevant question, which it will.