What if Finn doesn't join the Resistance as soon as he recovers? What if he has a strong aversion to signing up to any military organization in any capacity, even voluntarily, after his life in the First Order. He doesn't want a rank, he doesn't want to be part of a squad or do drills, he doesn't want to be ordered into battle, and in fact he doesn't want to take orders from anyone for anything. Just the idea of saying 'Yes, sir' to someone leaves a bad taste in his mouth. He thinks he might be willing, under certain circumstances, to actively fight the First Order as an individual, but that's something he's still thinking through for himself. However, with Rey away in secret Jedi training, he has nowhere and no one to go to. Normally the shoestring military organization that is the Resistance doesn't have space or budget for civilian hanger-ons, and though Leia is willing to make room for him, there are a vocal group of people against letting an ex-stormtrooper who won't fight stay around. Poe proposes they get fake married so Finn can stick around as Commander Dameron's spouse until he figures out what he wants to do with his life. Of course Poe is hopelessly in love with Finn