When adapting the 2019 LGBTQ romantic novel Red, White & Royal Blue for the screen, Matthew Lopez was careful to circumvent an R-rating. The film has a handful of sex scenes that stop short of full-frontal nudity — there's some bare butts and, naturally, shirtless men.
But it wasn't enough. Red, White & Royal Blue was rated R, meaning people under 17 would need to be accompanied by a parent or guardian to see it.
Another recent film with LGBTQ leads, the French romantic drama Passages, received an even harsher NC-17 rating, which would restrict people under 18 from seeing the film at all, and also keep it from playing in certain theatres.
There's guidelines, and according to the text above, the first movie followed them.
But someone has to apply the guidelines, and also what's fine or not changes over time. Something being rated R is ultimately an opinion.
It'd be cool if there were actual standards, or at least an appeals process so a movie isn't limited to just the first review if they feel it's not accurate.