What if . . . 1) It is actually significant that she repeatedly tells him her family used to lock her in the shed when she was naughty. He needs to retrieve some sort of special item from the shed that stops her from disappearing.
2) She is not actually disappearing, but the MC is the one who is being transported to an alternate universe.
3) There is actually a deeper reason for her disappearances and if they both have mutual feelings and end up together, the MC will die. After his first death, she did an experiment on her body that allowed her to disappear whenever their love is reciprocated, and then she traveled back to the time before his death. o.O
What if . . .
1) It is actually significant that she repeatedly tells him her family used to lock her in the shed when she was naughty. He needs to retrieve some sort of special item from the shed that stops her from disappearing.
2) She is not actually disappearing, but the MC is the one who is being transported to an alternate universe.
3) There is actually a deeper reason for her disappearances and if they both have mutual feelings and end up together, the MC will die. After his first death, she did an experiment on her body that allowed her to disappear whenever their love is reciprocated, and then she traveled back to the time before his death. o.O
4) She is a ghost.