YOU SAID:

I once dreamt that I had a girlfriend, and I was still sad.

INTO JAPANESE

私はかつて彼女がいる夢を見たことがありますが、それでも悲しかったです。

BACK INTO ENGLISH

I once had a dream with her and it still made me sad.

INTO JAPANESE

一度彼女と一緒に夢を見たことがありますが、それは今でも悲しくなりました。

BACK INTO ENGLISH

I had a dream with her once and it still made me sad.

INTO JAPANESE

一度彼女と一緒に夢を見ましたが、それは今でも悲しくなりました。

BACK INTO ENGLISH

I had a dream with her once and it still made me sad.