Well Jill and Bella are more of "commit to this girl before you get any reward" deals. Maya and Josy were basically relationship building from literally the first scene in the game, and their path is kind of a commitment all in it's own, locking you out of a few choices and making you feel like dog shit if you pick a different path in episode 8 by having them act extremely heartbroken.
Sage started under the premise of fuck buddies to help her destress while trying to work out what to do with her cheating boyfriend, but winds up being serious later.
Jill is basically as vanilla as it gets and you kinda need to dedicate a lot to her to get her and that's why she only sleeps with the MC on her route (she was literally a virgin, and the only real virgin in the game lmao), and Bella has morals that she has extreme trouble getting rid of. Bonus points that Jill considers Bella sleeping with the MC to initially be an act of betrayal cuz she knew Jill was interested in him. And likewise, Bella wants you to drop any pretense of a relationship with her anyway if you pursue Jill because Jill is her best friend and she wants her to be happy first.