This would be spoilers for sure, but have you considered a romance route with Cassie? There could be a story where the protagonist and Cassie become closer, marry for mutual benefit, and become closer friends.
94 days ago(+1)(-1)
I can't really black out spoilers, so I'll post a few images here to make it so people can avoid my response. 
Without too many spoilers, Kassie will still play a fun part in the game.
In Chapter 6 we'll be introduced to Kassie's on again off again girlfriend who will be romanceable, and let's just say that Kassie will be a key to unlocking a harem later on.