If those pics are sent through any of the facebook overall services, he's not the only one seeing them.
CoupleMemes
Community dedicated to memes that often hit a little too close to home. Respect the instance rules and remember that sharing these memes with your SO might 50/50 put you in the doghouse.
I'd wager the most common way nudes get leaked is by the recipient showing them off. Only way to ensure nude selfies don't leak is to not take them in the first place.
Unless you're using E2EE, that's pretty much a risk no matter which service - although obviously some are worse than others.
OTOH, it's a pair of boobs - anyone getting sanctimonious about something that there are billions of pics of out there is just a manipulative bullying asshole.
Everybody deserves privacy for their special unique body.
Anyone that doesn't want privacy can send it right to my inbox
And my axe