I honestly think things as they are perfectly fine. This is an adventure game, with sex. The overriding theme of the game is the story. Yes there are loads of sex scenes etc, but knocking up side girls really makes zero sense given he is very very unlikely to ever see them again, so you'd never even know if he did knock any of those girls up or not, think about the cave and the female aliens near the start of the game, he literally creampies every single girl, and I think he does that to a few he had already creampied earlier in the scene. The mc's main focus is the girls on the ship, aka as main characters. Knocking up the girls on the ship is different thing entirely and its obviously going to be part of the game at some point. I also think there could be some kind of jeopardy situation if you happen to knock them all up...they'd be utterly useless in their roles on the ship lol.