YOU SAID:

I don't know why you're not being a whole lot of fun today.

INTO JAPANESE

なぜあなたが今日あまり楽しくないのかわかりません。

BACK INTO ENGLISH

I don't know why you are not having so much fun today.

INTO JAPANESE

なぜあなたが今日あまり楽しくないのか分かりません。

BACK INTO ENGLISH

I don't know why you are not having so much fun today.