Handling in-game romance when the players are not romantically involved can be challenging. But ultimately it's just like acting. And we know that actors never end up getting into convoluted romantic entanglements with other actors...
On second thought: Handle these sorts of situations very carefully.
Luke: Why'd you kiss me? That's gross!
C-3PO: Oh, relax you noob. It's only roleplaying.
Luke: But she's Jim's girlfriend!
Leia: I didn't really kiss you, you know.
Han: Yeah, I'm cool with it. Nice roleplaying, Annie.
Luke: It's still weird.
Leia: Look, there is absolutely nothing weird about Princess kissing Luke.
Leia: I'm a, quote, damsel in distress, unquote. You're the, quote, hero, unquote, who saved me.
Leia: It's a natural literary progression.
Han: Wait a second. I'm the hero who saved you!
Leia: I don't think so, flyboy.
Chewbacca: Cheer up, old bean. With you around there will be plenty of opportunity to save her later.