Okay, so the fanfiction is on this site I believe.

In it, Jongdae is depressed because Xiumin, the boy he has a crush on and never told, moved out of the country and is getting married. Jongdae resorts to drinking and self-harm, thinking he is a screw up and a disappointment to the family. His friends see his pain and someone (I think it was Kai/Suho/Kill me because I can't remember) tries to make him better throughout the story.

There is also Taohun in this story, and I think Sehun has a crush on Tao but doesn't tell him until like... chapter 11 or 12 by mistake. Sehun ends up moving in with Tao because Sehun's parents disowned him after seeing Sehun with Tao. They thought Sehun was selling his body to Tao for money, since Tao is from a well-off family.

I know this isn't the best description to go off of, but this story was fantastic and I'm kicking myself for not bookmarking it. If you guys even have an inkling as to what this story is, please let me know! Thank you!