YOU SAID:
My girlfriend loved me by the full heart of hers.
INTO JAPANESE
私のガールフレンドは私を心から愛してくれた。
BACK INTO ENGLISH
My girlfriend loved me with all her heart.
INTO JAPANESE
ガールフレンドは私を心から愛してくれた。
BACK INTO ENGLISH
My girlfriend loved me with all her heart.
That didn't even make that much sense in English.