I’ll answer these lines by anim8tur a bit late, but still:
Lonely teenage girl with extremely low self esteem falling for the first stranger to ever show interest in her does not feel that far fetched to me.
The fact that she went to meet Kuro at the thought of losing her means she’d already developed a strong emotional connection with Kuro over text.
Aya had nothing and then comes Sei, who’s interested in her, who took the time to message her daily just to ask about her, who sparks her own curiosity, who awakened her sexual desires, the combination of all that makes it easy for Sei to become her reason to be alive.
This is soooo ridiculous. Like, are you a woman? Have you EVER been to dating apps, sites etc? When you create an account, you get like dozens of messages, and 99,9% of them are shit like “Are you a virgin? What are you wearing? Wanna see my dick? Have you got a boyfriend? Do you like cunnilingus? You have nice boobs, wanna lick ‘em!” and stuff like that. From what we can see, Sei did exactly the same. She started her perverted chat soon after they began talking. Daily, yeah, like for a week? So how do you think, are there a lot of woman who “develop a strong emotional connection” to that kinda fellows? None. Really, practically zero. Because it’s disturbing. Because it’s invading privacy. It’s uncomfortable. And it’s way more so when you are a lonely teenage girl with extremely low self esteem. So something like a girl falling in love with a stranger who writes in a chat “I wanna fuk u real hard ooohhh babe” is not even forced, it’s stupid and funny. It’s almost comedy. Thus this romance is pulled out of an ass. It’s called “bad writing”.