What I think is happening here is that 1) Author and Pink Hair were childhood/young school friends, 2) Author caught feelings that Pink Hair either rejected or invalidated insensitively, 3) Author blocked everything out due to being hurt and developed animosity towards Pink Hair, and 4) is now dealing with that block coming undone and her memories of it all coming back to the limelight.
Next few chapters will probably be flashbacks revealing both unreliable narratorship on Author's part and insight into Pink Hair's present attitude & actions and set them both up along with Blondie's epiphany to realise the not-a-triangle thing they've got going on.
Just guessing though.