A has hanahaki disease (which is a disease that causes flowers to grow in your lungs because you're in love, only goes away when the person with the disease knows that the person that they love requites their feelings. Cannot be removed surgically). They hide it well, but one day they slip up and their best friend B finds out (ok immediately I'm thinking of Bdubs as A and Keralis as B). B tries to help A, but A refuses, wanting to power through this.
A explains the disease to B. B insists on helping A even though A's days are numbered. A finally gives in. B comes up with a plan to hook A up with their crush, C.
B sets A and C up for a few events and stuff (aka dates). And they click. They have good times, the sexual tension is high, and get a little close. But nothing too much.
One day while the two are off on a date, maybe getting food (modern au?) and A needs to go to the bathroom to spit up some blood and flowers so they excuse themself. C comes into the bathroom while they're in the middle of puking over the toilet.
C questions, knocking on the stall. A tries to shoo them off, but fails when they start puking again. C tries to get A to unlock the stall, but A refuses so C casually breaks into the stall.
C sees A's blood along with the flowers. C is shocked so A takes that opportunity to bolt for it. A's condition worsens from there. They avoid C for a while, and hole themself up in their house.
Que "sad" scene of A eating icecream on the couch with B, wallowing in self pity like a moody teenager who just got dumped. B is trying to cheer A up but it doesn't work so B leaves.
A gets themself together and goes out and back to their normal life. C finds them, but A tries to push them away. C tries to talk to A, but again, A pushez them away. Then finally, C kisses A.
The key point to this story is that A stays strong unlike other hanahaki fanfics where the person with the disease easily succumbs to sorrow and heartache.