Well, he certainly found out she's been keeping her own secrets of one sort or another. And acquiring another language is a pretty big one. Particularly since keeping it a secret now that they're only the island means she pretty specifically didn't want him to know.

Which she didn't, because she'd had a change of heart, but she can't exactly explain her motivations without giving the whole game away.

What about second flashbacks?

I wouldn't mind seeing a Jin's dad -- Locke competency smackdown. Locke rambles through the woods and brings back a boar (finally!), only to see that Jin's dad has caught enough fish to feed everyone, and dried extras that'll last a week.

Well, there's that.

Calli: Ha ha!

Oh, if only there could have been an apple in that sequence!

I know Jin feels betrayed by Sun's, in fairness Great Honking Big, lie, but covering up criminal activities isnt an itty bitty one either. I thought that his visit to his father had made him realise that he wanted to put his marriage first, which he knew he hadn't been doing. I'd have thought he could forgive Sun, considering the circumstances.

Save me a seat on the Jin's Dad love train. I hope we don't get a second flashback where it turns out he was molesting the fish on the side or something.

covering up criminal activities isnt an itty bitty one either

I think he's primarily covering up her father's criminal activities, which is a dicier situation.

Jin should never have gone to work for her father in the first place, and then he really shouldn't have lied to her about what it entailed, but I think he felt he was doing everything for her. Finding out she had a secret life was too much to bear for him. He should not have walked away from her, but he has history of making bad choices.

I think he felt he was doing everything for her.

This is it. He could beat the ever-loving crap out of innocent people for her, but he couldn't forgive a lie? I know I'm supposed to feel sympathetic toward Jin, but I think maybe Sun is better off without him. She should totally go to Hurley for comfort. I'm just saying.

I didn't get the impression that he was leaving solely because she had betrayed him. I think that was part of it, but I think he was also realizing that he'd changed enough for her to want to betray him, and that he needed to not be around her if he wanted to change back.

he really shouldn't have lied to her about what it entailed

I get that he was caught in a cascade of decisions, but the part where he doesn't tell his wife that her idolised father is a hood? I do get that.

The part where he feels betrayed and storms out? It's not like he divorced her, or anything. As things currently stand, him not being able to deal is one of the most human reactions he's had to relationship events since the plane crashed. If it's going to take him some time to deal with huge news ... is that such a big deal?