Definition
The person with whom someone has a romantic or sexual relationship.
（某人的）伴侶；（某人的）性伴侶
Ever since she started dating John, he has been the man in her life.
自從她和約翰開始約會後，他就成了她生命中的男人。
There's a new woman in her life recently, and she seems quite happy.
最近她生命中有了新的女人，她似乎很開心。
Why don't you just tell him that you're not the woman in his life?
你為什麼不直接告訴他，你不是他生命中的女人？