I feel blue, because of the weather.

(날씨때문에 기분이 우울해.)

I am a little depressed right now, because I had an argument with my boy friend last night.

(남친이랑 말다툼해서 기분이 지금 안좋아.)
I just feel sad. I don't know why.

(나 그냥 좀 슬퍼. 왜인지는 모르겠어.)
I feel gloomy inside, because I broke up with him.

(그와 헤어져서 우울해.)