Honestly, I wouldn't mind if my partner was touched like that by someone close. Many people I know are very touchy. But I think it's because of our culture. Koreans have their own, so I get your point. I hope they resolve it asap.
idk coming from someone who’s affectionate with his friends (who have partners) none of them are mad about this and i wouldn’t be either as the other commenter said, maybe it’s a difference in culture but personally if i trust my partner like i should i wouldn’t get mad? and while yes boundaries are boundaries, u need to understand that in gay relationships because you’re dating someone of ur own gender and have probably had friends of that gender too, it’s normal to be affectionate with them since it comes naturally (not to say it doesn’t happen with het couples ofc)
The next chapter will probably come the excuse of "he's a guy and just a friend", like that would make it okay cause what are the chances the guy is gay and actually flirting, right? When you date you shouldn't allow anyone to get all handsy like that, it's disrespectful to your partner. It doesn't matter their gender or sexuality, no one likes to see their partner being touched like that, no matter who is touching them. Saying "are we even dating?" was so on point, cause the absolute disrespect that is allowing that kind of touch from someone else in front of your boyfriend is wild.