This is fuckin bullshit, from the beginning to the end.
Katsumi is such a bitch ! Toxic relationship or not, she clearly overused the kindness and love of Aki.
What she needs is not a new relationship but to learn why she always end up in a toxic relationship.
In this new relationship she's going to involves, Aki did all the hard work to make it possible. She's just a trophy that Aki won at the end.
And the magically turning gay at the end...please.