YOU SAID:

I really miss my ex-boyfriend, he was my best friend.

INTO JAPANESE

私は本当に私の元カレを欠場、私の親友だった。

BACK INTO ENGLISH

I really miss my ex-boyfriend, was a good friend of mine.

INTO JAPANESE

私は本当に私の元カレを欠場、私の良い友人だった。

BACK INTO ENGLISH

I really miss my ex-boyfriend, was a good friend of mine.