YOU SAID:
Nick is my boyfriend of two years.
INTO JAPANESE
ニックは2年間の私のボーイフレンドです。
BACK INTO ENGLISH
Nick has been my boyfriend of two years.
INTO JAPANESE
ニックは2年間私のボーイフレンドです。
BACK INTO ENGLISH
Nick has been my boyfriend for two years.
INTO JAPANESE
ニックは私のボーイフレンドで2年間になります。
BACK INTO ENGLISH
Nick has been my boyfriend for two years.
You've done this before, haven't you.