I searched Discord to list what Ocean said on the different girls so far: (main LI = romance + ending)
Bella: guaranteed main LI (Dom, Sub and normal routes
, could be different now that the game has taken a less dark route, won't be compatible with Amber)
Nami: guaranteed main LI (Nami/Bella is possible but she is otherwise probably the least compatible with other girls, Nami/Mila
not possible)
Sasha: guaranteed main LI and Ocean's #1 girl (as of August 2021), not planned to be part of any throuple
Sonya: guaranteed main LI and Ocean's #2 girl (former #1)
Mila: guaranteed main LI
Nadia: guaranteed main LI
Victoria: guaranteed main LI (and can be compatible with every other girl)
Nia: guaranteed main LI, wasn't originally a planned LI
Maja: main LI
Amber: main LI (two main routes, love or sub
, could be different now that the game has taken a less dark route)
Zara: main LI
Vanessa: main LI ("Vanessa doesn't just offer an MC sub route")
Marla: "All Teachers except for Marla are only lewdable but don't feature more (Relationship wise) " sounds like potentially LI?
Ayua: "can be romanced", but also stated since then that she is
not a LI, but she's a special case, it might change
Robin: "lewdable," very low chance of becoming a full LI
Layla: "lewdable" but no relationship and no ending
Coach Hill: "bangable", "hook-up/lewdable" but no ending nor romantic relationship
Karen: "lewdable"
Nojiko: "not a confirmed LI", "not planned to have Nojiko as an LI with an ending" - something to reveal about her to explain it
Elsa,
Celina, Nicole,
Genevieve, etc: ??? (nothing mentioned) the main LI list is not necessarily over yet although Ocean has a limit, and we might be introduced to some more girls (like the women's first team for instance).
Note: As of October 16, 2021, Ocean has said that the list of LIs can be expanded to more LIs but it is also possible that some LIs will be dropped, except for the eight that are listed as
guaranteed.
Note2: There will be no harem route. One was originally planned (although it would not have included every girl) but the game took a lighter tone, of healing, than was first thought, and the harem route does not fit the story anymore. You should still be able to bang virtually every girl in a playthrough but having a romantic relationship with several girls being aware of each other is a whole different thing. There will be throuples for the compatible girls, but no more than that.
I have summarized this myself, if you want to hear from the source itself, most of the updated info regarding harem comes from here.