Amber being gone for more than 6 months because of, according to SM, her ankle injury. She was gone for so long, and almost all mentions of Amber have been omitted: in their show Koala, the 2010 SMTOWN Live Tour, and the 2011 f(x) calendar.
Some fans even started blaming the other members (there were rumours that Amber had gotten into a physical fight with another member - either Krystal or Sulli - and debated leaving the group as a whole, although this was never proven), and blasting SM in general, because of the whole Unperson fiasco happening on their show Koalanote See the "Unperson" entry on the main page.
And in January 2011, Amber suddenly reappeared out of the blue, as she was seen in a SHINee concert. Hope began to resurface for the fans. Both a tearjerker and a heartwarming moment.
Krystal's fainting at the Lotte Duty Free Family Show concert due to overexhaustion. You can see her put a hand to her head, then visibly become shaky, then collapse.
What makes this even sadder is people IMMEDIATELY started ragging on Luna for not showing the "appropriate" level of concern, as did her other members. Thing is... you can CLEARLY see Luna freaking out, she's just better at concealing it than the others.
Victoria's "scandal" with TVXQ's Changmin - she posted a photo on her Weibo of herself eating a traditional meal... and then fans zoomed in on a reflection in a spoon and happened to see the reflection of a man, who they believed to be Changmin. Cue backlash.
Luna being called fat, a whore (because she allegedly flirted with some male celebrities), and being told she can't sing.
In 2013, Sulli was rumored to have been dating Choiza of Dynamic Duo. There's a 14 year age difference between them, and Sulli isn't exactly on the Korean public's good side (she was caught swearing on camera and then never apologized, and then later was criticized for not dancing the full choreography to "Rum Pum Pum Pum", instead holding her skirt and sitting still). But netizens... They really topped themselves this time. It's disgusting - hell, one netizen even called the others out, saying "All of you making sexual comments towards her are such trash;;; I can let swearing and other things pass but don't you think these comments are way too much for a kid who just turned 20 years old?" As of 18 August, Sulli and Choiza's agencies were forced to confirm that they have been in fact dating after pictures of them at a late night drive in movie theatre were posted.
Eventually the comments took their toll, and Sulli announced in 2014 that she would be going on an extended hiatus because she couldn't deal with the constant hateful comments from netizens. Netizens, of course, respondedsupportively.
Just as soon as news of her hiatus hit the web, Choiza's cousin posted pictures of him, Sulli and Choiza to his Instagram while on vacation at the beach with a caption saying "Cheers for kidnapping". Netizens who were already upset were even more angry and the netizens who were defending her instantly dropped her flat.
Netizens and FANS have not been kind at all to her since she announced her hiatus. The group was straight up in the middle of their Red Light promotions and had been winning awards and reaching number one on several charts... and then everything came to a halt because Sulli was taking a break. Fans aren't pleased with the idea of waiting another year for F(x)'s comeback and the repackaged album they were promised. Some are even suggesting going on without her, saying she's only the visuals of the group, she can't sing, etc. Poor Sulli.