I'm still madly working on the Case of the Crossdressing Earl, but the edits are finally coming through. I keep finding places, though, where I put a note to look something up later, and I haven't always found what I need.
Right now I need a poem. It can be in English or another European language that has been translated to English, and this must be before 1810 (as my characters must know it). It can be incredibly famous, or rather obscure, but suitable that a young lady would have read it.
The important part is the substance. There must be a marriage in the poem between two people who are only marrying for convenience. It can be for title, or money, or to fulfill an ancient prophecy, or to save a friend, but it cannot be for love. Neither party can love each other at the start of the story, or even by the time they are married. Bonus points though if the couple fall in love throughout the poem, and especially if they end up living happily ever after. Note — I'd prefer to skip poems about rape like the Wife of Bath's Tale, although dammit, it would have been perfect except for that bit.
Research done: Reading a LOT of Restoration, Renaissance and Medieval poetry, scouring themes for Marriage of Convenience — I even checked in TV Tropes, (and got out alive)