Lets flip this around a bit for some perspective.

A girlfriend comes across messages her boyfriend sent to his guys.

He's telling his friends how terrible his girlfriend is in bed, she does nothing and just lays there like a dead animal. Her vagina is so loose and unsatisfying, getting a secret fleshlight was the best decision of his life. The guys are all laughing at how horrendously bad of a lover she is, while the guy posts about how badly he misses his ex and how she rode him like a pornstar and knew exactly how to get him super hard and horny, and wishing his current girlfriend had one tenth of pornstar-girlfriends ability.

Oh, but the current girlfriend is a nice person.

I think the majority of this subreddit community would be absolutely crucifying this guy. Acting like it's not a big deal when the genders are reversed is just flatout sexism.

Also, while everyone is entitled to private conversations, this is the private life between two people. It's incredibly hurtful and disrespectful of your partner to air your shared personal life to others without at least talking about it together first.