黄泽理 管理学如何:"谈恋爱"英语怎么翻译

fall in love with sb. 爱上某人
be in love with sb. 在恋爱中

一般不直译.

意译:fall in love

'liufuduo'的回答 is fairly right, but the answer is still not complete.
"fall in love" means fall for someone, in this sense "be in love (with)" could be the same. It could be love from just one side and another person may still not know(e.g. "I'm so in love with her but she doesn't even know" or "She fall in love with him at first sight" or "Andy is in love"). In a word, the "love" here 可以是单相思或柏拉图式的精神恋爱。
If emphasize the word "谈" in "谈恋爱"（一定要有两个人做主语,e.g.relationship）, the translation should be "we/you/they"+"are in love"/"are in love with each other",表明彼此相爱着的一种维系着的状态。
相对地, "they fall in love with each other" should have a more precise translation "他们一同坠入了爱河",仍侧重最初“坠入”时的情境。

谢谢！

TO talk in loving

就是be in love with ,fall in love 是爱上某人还不一定谈上恋爱了呢.be in love 表示恋爱的状态,是指正在谈.

谈恋爱就是坠入爱河，译为fall in love with sb.
约会是date with sb.