ah that scene is not an attempt to make a well developed one its 3 lines, it was just a scenario i would love to hear and read. but dude people were predicting psycho ami before ayane's 2nd roof top appearance based on notable personality traits and various scenes despite the amount of gas lighting some people did to try and shut it down.
ayanes acceptance
ayane's kirin event and how he responded to it, his complete rejection of the very things she wants most 'baby and family', fucking around with everyone, probably more but it doesnt have to be a specific event that causes it. its also less seeing his darker parts than acknowledging them and deciding it doesnt matter, she decided to love him even if he decided to one day go around murdering people for sport. she lost her cut-off limit for acceptable healthy boundaries where a 'normal' person would go "nope you are not worth it" I think she would probably put up with anything at this point. she has become obsessively codependent on him. She has become this in a way the other girls have not yet but there are a few that are disturbingly close right now, such as noriko (she still has a clear independent streak no matter how much she says she would destroy and remake herself for him), makoto (still thinks she can 'win' him or change him but she seems close to just giving in), futaba (has a couple things, she thinks if she can fix herself enough it might change him, but her self esteem is so low the moment it crashes and burns I can see her giving in)
absolute unconditional love is the most toxic form of love you can get, its also heavily romanticized and seen as beautiful, generally in these cases though the love is mutual and not one sided.