I fully agree on choice. However, the nature of this game is not monogamous, and the various characters hint strongly at the planned combinations, even if MC is off-screen.
It is even set up so that not pursuing them, in most cases, makes their virtual existence worse, so intentionally cutting off routes in this game is abandoning them.
Short answer: the dev made it so people could play monogamy, but doing so is like buying Turbotax Premium and filing a sing 1040EZ.