It's not a good idea to put dialogue as your forward, but if you do, you should put in the speaker. When i first read the quotes, i got REALLY confused because i thought it was all one speaker in one situation, when in reality they were selections of text.  

Appearance: 5/5

The appearance is basic and straightforward, fitting your story. The pale colored background fits your simple text style. 

Plot: 10/15

Let me just put it this way. If you didn't say that it was angst, i would have given you a higher score, but you did. For an angst fanfic... there wasn't much of it. There wasn't a scene of Sehun waiting and waiting and waiting for Luhan to wake up, and instead you just said "after four days." This cuts out a lot of the angst in the story. Also, something else i noticed was that it was a little... convenient. For Luhan's bone marrow to match exactly, i understand that you probably wanted to show how "perfect" they were for each other, but for me, it's just a little too convenient.

Originality: 10/15

Cancer is a disease so overused in people's stories that it's a bit frustrating. I'm not blaming you for using it because its literally everywhere, from Hollywood movies to fanfics. This score isn't just based on your disease choice, but also the ending. You could have done a lot more with the ending. You could have had a scene at Luhan's funeral where Sehun is crying his eyes out, or maybe Sehun delivering the news to Luhan's parents. I understand that it's an oneshot, but the ending could have been a lot more powerful.

Grammar/Spelling: 17/20

It was much better than the past story i reviewed. There are a few verb choice mistakes, but i won't be emphasizing them.  

Characterization: 10/10

Luhan's and Sehun's personalities fit and stayed constant throughout the story

Flow:  8/10

I feel like your story could have had a better flow if you didn't change settings with headings. If you didn't have those, you would have more time to give your story more angst. Maybe, Sehun hints at his cancer during their car ride there. Or even not angst, maybe you show more of their relationship.

Overall Enjoyment: 8/10

It was pretty nice to read. I only have one criticism. Overall, it's a little awkward to read stories with POV's. You need to accept the fact that the majority of people on AFF are girls, so for them to see the story through a guy's POV is difficult sometimes. Just consider it next time. :) 

Total: 84/100