Why play a dating sim where a hot guy falls in love with you, when instead, you can play a VN where a hot guy is your ex boyfriend who emotionally manipulates you and makes you feel awful?
Jokes aside, this is a really creative way to reinterpret romance games- the goal of a romance VN is to win a guy's affection, so Kathy's desire to find a way to mend things easily mirrors onto the player. And although they don't have shared history with Benny as she does, the streamlined narrative centering on him easily draws them to think about him as much as our protagonist does. Seeing Kathy and Benny argue gains a strange emotional catharsis, and somehow we're still left wanting his affection...
Either way, I feel really bad for Kate... lost her family, doesn't seem to have any close friends, and gets stuck trying to get emotional intimacy by transactionally keeping her tenants and ex boyfriend around. Even Lewis tries to flirt with her to cheapen the rent...