Lina's reveal hits a lot of people quite hard.
My notes for Lina explicitly state that we don't know exactly what happened to Lina, but she was not full on raped. Of course sexual abuse is a wide spectrum. In this case, as stated, she had a group of friends. There was mild contact, she didn't mind. Couple of bumps maybe an odd spank of the but, the kind of touching that just happens in life and it's all in good fun. This, she didn't mind.
One time, one of her friends decided that she was fine with so much, why not just enjoy her body himself. Lina didn't know how to say no... But she sure as hell didn't say yes. Her friend to cock blind to notice what he was doing. A harrowing experience, but it wasn't just that. She did try to tell her other friends, but they didn't see a problem. She hadn't said no, they told her she had said it was fine. And she believed them, that it was her fault for not speaking up. Physically the event was not that traumatizing, but emotionally... she lost her trust in them, with pain and heartache and to be convinced it's her fault. But it still felt wrong. She doesn't like words anymore, but contracts are clear.
After this they drifted apart, Until she meets you again, Lina never really tried to process what happened. She certainly didn't talk about it with anyone (If Lin found out, it's not like those boys would still be alive). So when you're talking about how misunderstandings and why she kept the photo... She doesn't know either.
So that's the story of Lina.