I thought about this for a looong time. I didn’t want to use the same idea of space that you did, so I tried to think of something else. And it was really hard to put tragedy and space together and make a story out of it (for me at least)…

But I did it!

It’s not the best idea I’ve had but it’s something (and I’m sure you can make it into something amazing anyway ^^). It goes like this:

Tragedy: an event that causes tragedy.

‘EMPTY SPACE’

Main idea:
There’s a couple. They are happily together, living their life as usual couples. They want to go on a trip (choose which place, haha) and so they plan the trip and everything. They decide to go by a plane.
It’s the first time the girl is flying so she’s really nervous, but her boyfriend tries to calm her and says that it will be okay, that it’s not that scary, not that dangerous. That calms her a bit, but she still feels a bit anxious. The boy suggest the girl to sit right next to the window so she could see the pretty clouds & the nice view overall.

The plane takes of, it’s all nice and sweet… UNTIL. Something goes wrong.
The girl feels a bit sick from the flight and goes to the toilet. (She says that she’ll be right back.) Suddenly, the plane starts shaking, there’re dark clouds around it and people start to panic. The boy wants to get up and walk to his girlfriend, but the stuartess doesn’t let him, she says that it’s very dangerous, he asks, what about his girlfriend, the stuartess says she’ll take care of her. As she walks to the toilet, the plane starts falling, fast. She doesn’t make it to her destination.
So it all goes crazy, the plane falls, and right before it crushes, the boy sees the empty SPACE beside him.

In the end, the girl does not survive (neither does the stuartess and some other people), and the boy is heart broken, devastated with sadness, miserable, feeling guilty…

He thinks about the empty space beside him all the time. He even pretends to talk to her as if she was sitting beside him, but then he turns to look and there’s nothing but an empty space… He keeps talking to this empty space and somehow grows insane… He imagines her sitting in that place, smiling at him, laughing, but not saying anything. Deep inside he knows that she’s gone, but he holds on to that hope and thought that she’s still right here, with him, alive and loving. It could end at that. At how he has ‘filled’ this empty space beside him.

The tragedy in this:
Of course the plane crash. And also the fact that he keeps on holding to a false hope. It’s tragic that he keeps talking to that empty space, in his thoughts imagining it’s her…

‘Space’:
I somehow feel that the ‘space’ theme isn’t enough in this, but I really hope it is. As it ‘becomes’ his love, in his mind that is… (if that makes sense..)

Characters:
Onew maybe? And some girl I can’t think of… You can choose it yourself ^^

Length:
I’m not very sure about this, but I guess a few long chapters would do, or one loooong chapter. It depends on how fast you can write (since because of me you have less time left :( )

Songs for inspiration (inspired me for this plot):

Secret – Empty Space:
http://www.youtube.com/watch?v=5vaetJi9Wrc

+ the wrong (?)  lyrics that inspired me:
http://www.songlyrics.com/secret/empty-space-lyrics/

Click B – Empty space (for this I found only the lyrics, no song):
http://popgasa.com/2011/11/08/click-b-empty-seat-%EB%B9%88%EC%9E%90%EB%A6%AC/

LED Apple – Let The Wind Blow:
http://www.youtube.com/watch?v=rriUBjX_fNo

Aaah, I think this doesn’t make much sense (and is very unlikely to happen in reality…), but I (once again) hope that you will understand my trail of thought, haha

Sorry it’s so late again :/
I’m taking away the precious time you could spend on writing… and I’m really sorry about that Y_Y

But I know you can do it! ^^ Hwaiting!!
For questions – feel free to ask if you have any!