Monogamy/Harem Route (Default): Val is only allowed to be sexually involved with the MC.Also question, I haven't reached yet, but see paths, is sharing route, kind of the same as Harem, but Val can have some fun too, where Harem is mainly just us having fun and Val can have fun a bit with the other Harem members only?
Open-Harem Route: Val is allowed to also have sex with Rena, Annestria, and optionally a couple side heroines.
Sharing Route: No restrictions. You can choose for her to have fun with anyone you want.
As for the MC, you're free to decide your own rules. You can keep Valerie to yourself while still banging as many girls as you want.