What no and yes actually means in Korean
One thing Americans say that Koreans do differently is the word yes or in Korean (ne) and no or in Korean (ani or aniyo) the way Koreans say it does not mean no and yes. Yes means yes, I agree with what you are saying. It can also mean I am listening and no in Korean means no I do not agree with what you are saying, for example, So you didn’t eat bulgogi yesterday. The person would respond yes or I agree with what you're saying if she did not eat bulgogi yesterday.
Good observation, and something to keep in mind when speaking English with a Korean to avoid misunderstndings.
"You don't think I look fat?"
"Yes" is the natural response for a polite Korean.
"Don't you want to be with me?"
"No." signifies a desire to continue the relationship.
It's best to clarify with a follow-up line right away.
This rule does apply to English on occasion. At least, it does where I'm from. For instance, my mother might ask something like, "you didn't want coffee?" and in response I'd say yes or no depending on whether she was right and I agreed or she was wrong and I disagreed.