Few things to say about Kaija.
What was the end goal in her mind though?
What if MC wanted marriage/children?
What if she actually fell in love with someone?
The reason why I find her irredeemable on "friend" path is because I can't stop thinking of above.
Naturally, love and "friend" path make Kaija a completely different person, and love path would be (somewhat) possible to answer by simple: "They go for it and she comes clean".
"Friend" path just baffles me.
How did she think it would end? There is simply no long-term scenario where it doesn't come crashing and burning down worse than Hindenburg.
She leaves scorched earth behind, while hoping to have trust from the person whose life she destroyed?
If MC develops genuine feelings based on complete lie, what then?
For role-playing sake, think how utterly devastated MC in love with Kaija would be on 0 points chapter 1 run.
Just think about it for a minute. Here's a guy, in love with his childhood friend, she returned his feelings, he's happy...then it turns out all of that is a lie. She doesn't love him. She was with him only because it's her job.
Again, I am talking low-points, still love her option taken scenario.
Love path gives completely different story, and one where I can see why people would be willing to forgive and forget. She suffers and genuinely feels sorry for what she did.
Bench scene is day and night difference. Shower scene (one with achievement) shows how messed up she gets.
Even on this one, though, I have to ask similar questions. How did she think it will end up?
She entered relationship for all the wrong reasons. That sucks. Her actions after she developed feelings for MC change the narrative completely though, and redemption feels deserved.
Not that I'm going to pursue romance on any of the paths, but I am happily following high-points route to see her development there.
Kaija is such an amazing character, and just like an amazing movie/tv show villain, I love everything that happens around her.