This film is "Midnight Sun." The movie is about a love between a boy and a girl. The girl has XP, which is a disease. So, she can't go out in the morning or the afternoon. Therefore, they only can only enjoy the night.
There are some famous lines in the movie:
"I'm really busy during the day, but I can be free at night."
"Having someone, that's the best part."
"And if you need me, all you have to do is look up."
L.L.F editor-in-chief Yu-Min Kim