I know this is a bit late, but regarding Sheryl and Alto's living arrangements:
Sheryl's independence was a point of contention between the two during their talk in episode 22. Although Sheryl accepts Alto's emotional support, she doesn't really want to be "looked after" by him. With that point in mind, karice's revelation does seem unremarkable (retrospectively speaking, of course).
There's an element of this "tension" that plays out here in episode 24 as well. ("Tension" is perhaps not the right word, but I use it here to mean being torn between two states of mind.)