In real life, Maddie-kins liked to visit Masada after her trips to the mall. Everyday she visited him, until they gradually became more close.
They first had a Tutor-Student relationship, which turned into a Friendships relationship, and then into a GF/BF relationship which gradually led to occasional smecks, which is why Madotsuki has an event activated when she sleeps in his bed. But we'll get to that later.
One day, something went wrong, omg! :O
They forgot to have protection. Which is why everything goes "OH NOES!" during the event. Red lights flashing, it was an emergency! Masada was panicking. Maddie-kins, in her dreams, sleeps in the bed to activate the next part of the event, which may symbolize her sleeping on a hospital bed, what with the emergency panicking.
The lights were red.
She (maaaaay) have gotten a miscarriage.
After everything was over, she was able to go outside. It was a barren place, where the only living things there were UFOs. Probably people from afar gossiping about her. During that time, she felt so small. So small that she could fit through a hole.
In her dreams, this was literal.
The path started with a set of staircases, sad music, full of sadness, and ended with a crying creature, alone, in a pile of rubble.
Maddie-kins, meet...your lonely unborn fetus!
No matter how much she wants to kill the memory of it, it's still there, merely expressing its sadness at not being able to have a chance at life. Being alone. In the part in the afterlife where fetuses go.
That is why she put those memories in a room protected by flames, where she would forget them eventually and later be foolish enough to go through it.
It's like her version of DELETE F***ING EVERYTHING except it involves a Recycle Bin.
tl:dr, It's hard to find a theory without genitalia.