YOU SAID:
I am sad cause my boyfriend sleep earlier
INTO JAPANESE
彼氏が早く寝てしまうので悲しい
BACK INTO ENGLISH
I'm sad because my boyfriend goes to bed early
INTO JAPANESE
彼氏が早く寝るので悲しい
BACK INTO ENGLISH
I'm sad because my boyfriend goes to bed early
That didn't even make that much sense in English.