He might be doing it for attention, unless this is really casing him suffering
Think about how's he acting, Like do you notice him showing different personality changes or does he notice tending to forget about core events that any normal human could easily remember? Does he seem dazed or like he's not in control? Does he feel a lost in identity? If so he may actually have a mental disorder.
And PTSD doesn't necessarily have to be from abuse, it can be from any kind of traumatic event, like war, natural disasters they have been in, verbal abuse or extreme stress. My grandmother had PTSD and it was because she saw her brother get caught on fire and become severely injured from it. Dissociation can also be from Depression, Anxiety or any other high fuctioning mental disorder.
P.S. I am not a trained psychologist, I have just heavily researched the topic and has taken a psychology class.
If your friend is really concerned about possibly being dissociated, I would encourage him to tell his parents and/or contact a professional/doctor for a proper diagnosis.
