The short answer would be, create saves.
The slightly more explained answer is that I don't want to give a detailed answer, especially in a public forum, because:
1. in a story driven game I would see that as a spoiler.
2. I would like to be able to create a different scenario than the classic formula. If harem game and date everyone then = everyone happy at the end and everyone fucks around with all the others. If no harem game and date everyone then = bad ending, everyone mad at Mc and the others. Why can't it be something more than that? Why can't the currently not connected Li's also influence each other positively, other than everyone fucks each other, or negatively, other than everyone hates each other? But something like that would put huge expectations on the game which I don't know I could deliver on with my limited skills as a writer. Hence the same answer as above, create saves.