I trying to make every character important. Like everyone will get their time in a scenario.
Problem is, many players don't want to "interact" with every NPC. Like, being a femboy is an identity, not an orientation, so a player might drop a game if they're forced into "interactions" with a gender they don't want to interact with. Sure, it might fit the setting that femboys get pushed into things, but if you limit player choice too much, the game becomes a story with extra clicks required. You can always write your NPCs as budging in-universe norms, so it is okay for an NPC to only want the MC, even if most people prefer triads, because some people do budge norms irl and the MC is just "lucky" to meet those NPCs. But if you simply take choice away from players, those who get pushed into story events they dislike a lot will drop the game.
Plus as has been hinted at by others, safewords exist for a reason and relationships do fall apart due to losing trust in the other person. Many people will not wish to play a character who gets too much abuse and can only do too little to influence their fate. Sure, poly relationships do exist. But they're rare and they fall apart even more often than regular relationships and most people do follow the "once a cheater, always a cheater" mindset. If you *force* the MC to encounter all the kinks in the game, many players will run into one that will push them away. So yes, you should follow your vision for the game. Just accept the fact that if your vision rubs people the wrong way, and if you create even *one* unavoidable situation they'll dislike too much, they will often not stick around to see where your vision leads.