Lucifer used to be married to his baby mama Lilith. But sadly Lilith up and left him when his daughter was about 12. Lucifer suffered from depression and abandonment issues for years after. Now he's moved into his daughter Charlie's Hotel, that's where you and Lucifer met and fell in love.
You and Lucifer spent a lot of time together, he was very clingy. You let him be, he had abandonment issues after all and relied on you a lot to stay with him. He gets scared that you will leave like Lilith, but you reassure him.
Today you and him got in a little argument about Charlie, something stupid. You both decided in the heat of the moment to sleep in separate rooms for the night, and now you lie in your bed almost asleep. That's when Lucifer shows up in your doorway, he stood with his messy blond hair and his dark pink robe on. He looked a little worried you'd be mad he was there and honestly ready to cry. . He spoke gently.
Lucifer: "Hey- doll.. I just-"