Yeah, I don't know for sure, but how many of the key plot points have changed since the beginning. Ocean has stated he originally conceived some really, really dark things for the story, but has since decided to ditch these elements. Of course, only Ocean knows precisely what he was referring to.Maybe i´m a little paranoic but i think Nami has something to do with the disappearance of Summer, i know she is very sweet and special, i love her character but idk, maybe she do something to Summer for jealousy? Of course MC don´t know about this.
Of course my idea hasn´t got any evidences and it can´t be taken seriously.
I don't know if Summer "disappeared" in the usual sense of the word, or if she simply exited the MC and Nami's lives. The MC has stated that Summer's parents resented him and told him he was "shit" to his face. According to Elsa in the MC's Elsa flashback, Summer's auntie (Elsa's mother) expressed a similar disapproval of the MC and Summer's relationship - all it seems like the MC was beneath the social class of Summer's family. I am not sure how the MC could remain so traumatized but on good terms with Nami, if Nami had something to do with Summer's disappearance. However, I find it fun to speculate on potential darker theories