There is a harem ending, and that was never retracted. We certainly didn't retract it. You can have a romantic attachment to as many or as few as you want, but the friend route is necessary for every character up until their story arc is complete.
And yes, you can choose to have only one girl too.
Every interaction with a main character is a heart check, so if you aren't on their route, you won't reach those routes. And every route is dependent on the character. Xia for example would have sex without being a relationship. Rylee wouldn't.
And yes, there is a sci-fi flair to the knee brace and happy interactions heal the character's knee.
Everything we have said original has been and always is going to be in the game.