Her lies are not hurting anyone. They are not hurting anyone now, but soon they will. When her lies are revealed, everyone who believe in them will fall and when they do so will you." Marinette's cold voice and cruel words echo in Adrien's head. The fact that they turn out to be true just drive the pain in more.
He had thought Marinette was just being selfish at the time, when she transfers class and cut ties with her friends. He had thought that she will eventually realize her mistakes and apologize to the class. But she didn't. Instead she just made new friends and start ignoring them. Her new friends didn't believe Lila and were continuously trying to expose her. He had tried to get them to stop by telling them her lies weren't hurting anyone. However, they just snarl at him or laugh in his face.
He had realized now looking back at on it, that Lila's lies had hurt his friends. After Alix and Kim were suspended from their teams for attacking Marinette, they miss important competitions where there were college coaches scouting. Even after they got back in, there was an unspoken tension between them and the rest of their teams due to the fact they believe in Lila's lies. Due to Lila's stories of her doing extreme sports, they tried to imitate her and ended up with injuries, which prevent them from playing sports. During these times, new students join and since they got along better with the team and were just as good, they stay, replacing his friends. From what they shout at him, when they visit him in Juvie, they couldn't get into their dream colleges and jobs.
Kitty Section broke up with Luka leaving. Luka apparently didn't believe Lila's lies. He also didn't like Lila's "tips" for the music they should play. After a huge argument with the rest of the band, when the band was booed off stage in a competition, Luka went solo. From what he heard from the wardens and others in Juvie and what little he saw on TV; Luka was on his way to becoming a star. The rest of the group through keep taking Lila's advice and was banned from all music competitions.
The Ladyblog was labeled as a tabloid by the media due to Lila's stories. Alya didn't see that Lila's interviews were harming her reputation as a journalist and keep posting them. Eventually she was sued by the various celebrities that Lila claim to know for slander and defamation. From what he heard, her family was now in debt.
Nino, like Kitty Section, took Lila's advice on his films and like them lost competitions. His and Alya's parents also found out about them dumping their babysitting first on Marinette then on their other friends in the most horrible way possible. Mylene didn't know about Etta's allergy to dairy and had brought all three kids ice-cream on an outing to the park. A passerby thankfully managed to call the ambulance and Etta was fine. However, the hospital call Etta's parents when Mylene couldn't answer their questions. Alya's parents were furious when they heard the situation. Mylene apologize profusely and managed to get out with no trouble, since she had all but forced to babysit by Alya who wouldn't accept no for an answer. THe guilt through still take its toll on Mylene and eventually she and Ivan brought up. Alya was grounded by her parents and her allowance take away to pay Marinette and her other friends. Nino too suffer the same fate.
Nathaniel broke off with Marc, when Lila said she would be better as a writer since she knew so many writers. Marc was invited by Marinette to join her group of friends. Marinette once again helped and introduced him to another artist from she met a design competition she joined. From what he heard, the two got along great and had work together to join several writing and drawing competitions. He learned, from what little bits of gossip he managed to hear from the other classes (before Lila draw the attention back to her), that they would be interning with a large publishing company after graduation. Nathaniel, on the other hand, somehow got in the middle of a fight between two football players and his hand was damaged. He would never be able to draw again.