As for Jin leaving for Ji-Yeon. I thought it was fairly believable that he would stay for Sun. I mean, yeah, you have a daughter, but that's the love of yer life pinned to a wall about to drown. Idk, I think I'd stay in the sub w/ Sun tbph.
You're not a parent. If you ever become one one day, you'll see it differently.
When it became obvious that he wouldn't be able to free her, he should have left. There's no reason to sacrifice yourself needlessly like that.
Proud to be the Unofficial Secret Illegal Enforcer of Eyes on Final Fantasy! When I grow up, I want to go to Bovine Trump University! - Ralph Wiggum