I Need A Man, I Don’t Mind Being Second or Third Wife

I love enjoyment and I've been with my current partner for almost eight years now. He is a fairly successful businessman and was married twice. His two wives don't live with him and they are cool.
He has told me from the beginning of our love affair that he is not keen on living with a woman, I live in my own house and he is supporting me with money.
I have a son and would want at least a child now that I'm approaching 40. He said he would go along with me having his child but he's not getting married to any woman again. Do you think he will change his mind?
I don't really mind even if I become is third wife. How can I convince him to make me his wife?
– Ms. NK