Or just a good political match. They are children of neighboring nobles. It should be rather common for those who depend on the steady flow of commerce to support each other and grow closer through marriage. And while true such unions might start as a convenience, it's also not uncommon for them to evolve into one of love or mutual respect.
Thank you both for answering so seriously to my jokish/sarcastic comment as someone who enjoys the fake dating trope. It possibly being an excuse on Rufus' part would also make my day