翻译“他和她谈恋爱已3年了.”

He and she have been in love for 3 years.

They have been in love for three years.

He has been in love with her for three years.

谈恋爱不能直接用love来翻。fallen in love是坠入爱河(不可能三年一直都在坠吧？)，been in love是相爱。“谈恋爱”跟“相爱”之间还是有点区别的……

They have been dating for three years.
或
They have been in a relationship for three years.
都是比较准确的翻译。

He is in love already for three years with her.

He has been in love with her for three years.