me neither, at least I hope not ^^ I love that Jin just asks straight out what he wonders about / fears - I mean everyone has a history.
But like I said I don't think so, cause I just can't picture it and I think they'd act differently, but who knows.
yh
Spoiler.
They did speep together and not just one time.
Jin saw Angelo coming out of Ei's room with the "after sex" look.
It bothered him because deep down he loves Ei but never reliaze. Ei never confesses and acts indifferent. That's why it takes them so long to be together.
i dont think he slept with Angelo