There is a big difference between being intimate to the person you love compared to watching a video and not sure whether or not something maybe happening that you don't know about.
If you don't want her to selling nudes it's your choice to leave her and people may agree with your decision or not But if she does that after promising she would stop it means she is ready to lie to you.
What would you choose to do if you were him? I would say more of the same but a lot worse.
Natalie goes out of her way to engage with her millions of fans, offering exclusive private content along with her amazing videos.
OnlyFans seemed like the easiest option.
Use other talents she has, i'm sure she has others than that.