YOU SAID:

i have been dating my girlfriend for nearly four years

INTO JAPANESE

私は4年近くガールフレンドと付き合っています

BACK INTO ENGLISH

I've been going out with my girlfriend for almost four years.

INTO JAPANESE

私は4年近くガールフレンドと付き合っています。

BACK INTO ENGLISH

I have been going out with my girlfriend for almost four years.

INTO JAPANESE

私は4年近くガールフレンドと付き合っています。

BACK INTO ENGLISH

I have been going out with my girlfriend for almost four years.