Phasma and Kylo have both been pining and awkwardly flirting with each other for ages. Playful banter while they're sparring in the gym. Nerding out together over weapons and fighting styles. Low-key flirting on missions- he compliments her sharpshooting and she preens all day, she's impressed when he twirls his lightsaber so he starts doing it all the time to show off. She gives him her dessert rations claiming she doesn't like sweets, but really she noticed how much he loves them. He pulls strings with Snoke to get her stormtroopers the newest blaster rifles that Hux said weren't in the budget.

Neither of them realize what they're doing or what all these warm fuzzy feelings mean because they are both giant emotionally-stunted children. Their relationship is Purely Professional. No, really.

+ For matchmaker!Hux who is the only emotionally mature adult in the bunch and thus the one who realizes what's going on before they do.