YOU SAID:
The only girl I've ever loved has left me.
INTO JAPANESE
私が愛した唯一の女の子が私を置き去りにした
BACK INTO ENGLISH
The only girl I loved left me behind
INTO JAPANESE
私が愛した唯一の女の子は私を置き去りにした
BACK INTO ENGLISH
The only girl I loved left me behind
That didn't even make that much sense in English.