YOU SAID:

my bestfriend thinks we're only good friends..

INTO JAPANESE

私の親友は、私たちは唯一の良い友人だと思います.

BACK INTO ENGLISH

My best friend thinks we are only good friends.

INTO JAPANESE

私の親友は、私たちは唯一の良い友人だと思っています。

BACK INTO ENGLISH

My best friend thinks we are the only good friends.

INTO JAPANESE

私の親友は、私たちが唯一の良い友達だと思っています。

BACK INTO ENGLISH

My best friend thinks we are the only good friends.