Thanks! Ocean himself stated that he dislikes harem, he wants his games closer to reality and so you will have to choose with whom you want to be together. As said, threesome relationships are possible, but not so easy to get.
While you might can get into bed with several girls for fun, if you want a relationship with Miru, Leia, Zoey, Dana, etc. you will have to work on these relationships. Meaning, you will likely just gain enough stats and traits for 2 of them to be in a longtime relationship.
So a swooning harem is not in the cards.