It's a shame the "harem" tag is just bait. The women don't know about each other, and you can't have all of them. Depending on who you start a relationship with, another part of your love interest is excluded. For example, if you're in a relationship with the "MILF" who has the child, you can no longer date one of the twins, and that has nothing to do with "harem." "Harem" means you get all the women, but as the game currently is, you can cheat to get around "harem" because the women don't know about each other.
P.S. Thanks for removing the harem tag.
(Translated with Google.)