YOU SAID:
i am always sad when I should be happy
INTO JAPANESE
幸せになるべきときはいつも悲しい
BACK INTO ENGLISH
Sad whenever I should be happy
INTO JAPANESE
幸せになれば悲しい
BACK INTO ENGLISH
Sad to be happy
INTO JAPANESE
幸せになるのは悲しい
BACK INTO ENGLISH
Sad to be happy
That didn't even make that much sense in English.