
But they are not best friends, right?

Technically, *you* would be the one intruding on *them* (if you were like Jin's friend, and your friend had already been dating him).
But I agree, they'd have both been better off if Jin had told him from the start, rather than ask him if *that guy* was his crush. Stake your claim clearly, you stupid boy!!

That's why you can only be sad, not piss off because they didn't have to tell you. They should but that's not their obligation, either.
OKAY HONESTLY THO IF I WAS THE ELEMENTARY SCHOOL FRIEND ID BE PISSED AF FOR NOT KNOWING THAT MY BEST FRIEND IS DATING MY CRUSH LIKE BITCH WHAT THE FUCK