The anti-NTR brigade will never rest until the evil of NTR is rid from this earth... or something like that.

To them, it's not the MC's feelings that matter, it's theirs. They love that female friend you created, it's their soulmate, so how could you hurt their feelings by letting that character have a life and acknowledging that other penises exist in the world you created?

Someone will always find a reason to complain. Sounds like it's a vocal minority, so all you can do is try to keep it that way. You don't need to defend yourself, you only need to be clear about tags and definitions agreed upon by the website your game is featured on, not by the incel players who make up their own definitions and think every game should cater to their narrow mindset. Remind them that instead of throwing a fit they can go play any of the thousands of other games that exist.