I'm older than you think and idk where you live but virginity has never been a hushed topic where I am lol. High schoolers talked about sex all the time and who was losing theirs. We had books about anatomy and sex and we read them out of curiosity. It's not like knowledge didn't exist before the internet and everyone was an uneducated idiot (I mean even with the internet, we still have a bunch of those.)
Funny how so many other mangas both around this time period and older feature first times but don't have butt bleeding and tearing or an author that focuses on sadism. But I'm the one not using my brain, sure.

You hate the author for being old school? Anus ripping apart for sex is a fetish?
Uhm, how about, two HIGH SCHOOL boys trying anal for the FIRST time and it was one of the MANY cases where it went wrong.
Before 2015/2020, talking about losing virginity was STILL a hushed topic. ESPECIALLY unheard amongst homosexual people. Even GIRLS back then, when they lost their virginity during teenage years often spoke of how painful their first time was. Losing your virginity in your teenage years is by many expained, to be painful, messy and unprepared. Which ALSO happens with 2 high school boys. It isn't a fetish or anything.
Sometimes even first kisses are messy and sloppy if you're also doing this stuff with virgin-like someone. These two boys were inexperienced, teenagers, and virgins, so to call a butt bleed a fetish or an impatient hormonal teenage boy awful is your own mind, incapable of doing the logic work.
Honestly, I can't stand people like this. Use that thing you call a brain.