Craig Turner was 59 when he was found dead in July at his Los Angeles home from a self-inflicted gunshot wound.
Speaking to BBC News, Tina Turner said he had seemed fulfilled in both his professional and personal life after finding a new girlfriend.
I still dont know what took him to the edge, Turner said, because at that stage he had said to me that he had never met a woman that he felt that way about.
He was bringing her to meet me [for] his birthday in August. He had decorated his apartment, that I bought him years ago. He had gotten a new job with a prominent real estate company in California, [which] he was very happy with.
I have no idea what pulled him down, except something that followed him with loneliness. I think it was something with being alone.
But when I think that, why didnt he call the new girlfriend that gave him the lift?
She added: He was an introverted person, he was very shy, so I didnt know either, except now when I listen back to our last conversations, I notice a change.
The last few times we talked, the conversations were different, and I didnt know that until after the suicide.
Turner also discussed how her life had changed since her marriage to her long-term partner Erwin Bach in 2013.
She has written about her life in her new autobiography entitled My Love Story.
Not long after her honeymoon she suffered a mild stroke, she then had cancer, and kidney failure and doctors told her she would die if she didnt take treatment for her kidney.
So I said well, if its time . I felt like Im in my late 70s, my mother died at 84, my sister died at 74 and I thought maybe this was my time.
In Buddhism you accept the life and the death. I was ready, I just thought it was my time.