Originally Posted by Cankerskull
Before the island, she learned English because she wanted to leave Jin, and never spoke it in front of him so that he wouldn't catch on.
In the Sideways, she's not married to Jin and seems to be in love with him. So there would be no reason for her to learn English. And if she did, there would be no reason to hide it from Jin.
But, she did say that she wanted to run away with Jin....so there might have been a reason to learn English.