Oprah Winfrey doesn't want to get married in case it ruins her relationship.

The 59-year-old media mogul has been dating Stedman Graham for 27 years and while the couple couldn't be happier, Oprah thinks getting married could change things.

Speaking to Andy Cohen on 'Watch What Happens: Live', she said: ''I don't know if I wanna do that.

''It's really good right now, and when you add that 'wife' thing, then too much.''

Oprah recently praised Stedman for his support when her TV network initially struggled.

The TV star launched OWN (Oprah Winfrey Network) in January 2011 and due to poor ratings, Oprah took over the role as chief executive officer and chief creative officer in July the same year.

Viewing figures continued to fall in 2012 and by May 2012 the channel's losses were estimated at $330 million.

However, new show 'Oprah's Next Chapter' - which has featured interviews with huge stars including a two-part tell-all chat with disgraced cyclist Lance Armstrong - has improved the channel's standing and it will break even later this year, and Oprah credits Stedman with helping her to get through it.

She said: ''He was amazing, he said, 'You can't even think about quitting. You've been in cruise control, it's going to turn around but you've got to do the work.' ''