If they can consent and did, it's nobody else's business.
It has issues in the teen years, but from about age 22 onward, it seems to match well with [US] societal mores.
The most common rule of thumb you hear is age/2 + 7. So for a 20 year old it indeed 3 "school grades" (more commonly known as years) but for a 30 year old it's 22
Who are these "adults" that constantly need validation and advice from strangers on the internet? How can they seriously expect to get any useful answers? Grow the fuck up, shut down your computer and talk to your fucking partner.
Similarly, if a bunch of people in real life are calling you an asshole for something you did, you were most likely an asshole. Posting some edited version of what happened to have a bunch of internet strangers soothe your feelings isn't going to change that.
"My boyfriend is wonderful but his feet smell" "oh my God dump that stinky-ass clown".
Basically, instead of "communicate with your partner", everyone defaults to "get a new one".