In love, Saturn in Sagittarius isn't chasing passion or a light adventure. What this person looks for is a partner with a settled worldview — someone with whom a serious conversation doesn't collapse into awkward silence, and who, on the contentious questions, holds an actual position rather than a paraphrase of whatever opinion is currently in vogue. Falling for someone happens slowly here. There's a long period of watching, of testing against time and circumstance, before anything is allowed to count.
In my experience, people with this placement often choose a partner who is older, or who comes from a different cultural world altogether. That kind of union tends to feel more natural to them than marrying someone their own age from a couple of streets over. They respect the other person's path, they don't fuss over small things, they hand over a good deal of freedom. But on the questions of principle — how to raise children, how to handle money, which country to build a life in — they stand their ground, and they rarely come to the table with much of a compromise to offer.
The shadow side in love is just as recognisable. Saturn in Sagittarius slips easily into turning a partner into a pupil: correcting, instructing, steering them onto the right road. A partner with a strong character of their own argues at first, then tires, then drifts. It can be especially hard going when someone with this Saturn ends up with a lighter, more in-the-moment person — someone for whom life isn't about proven principles at all, but about how the day happens to feel.
What tends to last is a partner with their own strong picture of the world, one who isn't afraid to push back. What doesn't last is silent agreement offered out of politeness, an attempt to re-educate, or — the reverse — a quiet hope of being re-educated. The good relationships, for this placement, are built like a long conversation between two grown adults, not like a teacher and a student sharing a desk. None of this is fixed; it's a pattern worth noticing in yourself rather than a script you're bound to.