Buffy: On-screen canon. Romantic fluff followed immediately by tragedy.

Ahsoka: Headcanon. With both Lux and Kaeden, she's shown to be awkward and unsure what to do, especially since it's not a good situation for pursuit-even more so with Kaeden, since she's totally lost-and she's capable of letting them go. I do think she could've met someone and had fun for a brief time. Maybe more than one someone.

But she was already head of Rebel intelligence and had a pretty isolated life.

Yvaine and Cassandra: The ones we saw on screen with their canon love interests. Sweet fluff followed by dramatic fantasy action-adventure climaxes in which one half of the ship leaves the other before they wake up to go do an important thing.