YOU SAID:
i think i'm in love with my best friend
INTO JAPANESE
私は親友と恋に落ちていると思う
BACK INTO ENGLISH
I think I'm in love with my best friend.
INTO JAPANESE
私は親友に恋をしていると思います。
BACK INTO ENGLISH
I think I'm in love with my best friend.
That didn't even make that much sense in English.