
He better not have fucking called him boss.

Dude why KYS
Look I get that itād hurt like a BITCH if he said that out loud to Matthew but Jinās head is messed up. He might be having a traumatic flashback.
By the effect of trauma, people undergoing trauma become incredibly submissive/powerless like Pavlovās dog, so when the memory or situation repeats in flashbacks they go back to the traumatic surrender/incapable state.
So thatās if it was a traumatic flashback.
If itās not a flashback and just a hallucination, Jin looks like a total asshole who imagines his rotten boss having sex with him in place of his partner. But here comes character design/individuality. With how psychology works, people form unconscious sexual associations in case of a skewed power dynamic in any relationship. It can be a mom, dad, aunt, teacher, abuser. Itās like Freudās theory of Oedipus complex from the human psychosexual framework.
Where one is inevitably in surrender for lack or loss of power during trauma. (Iām saying trauma is common whether or not itās a flashback.)
So although it sounds too deep, when pieced together in the larger narrative itās often palpable for the audience.
So this is just my understanding of his character, a level deeper than the surface so sorry if it feels far fetched or turns out to be. But an author does think on a level deeper to develop characters, so I came to making this guess.
Tf wrong with him..