Nicole Kidman knew she wanted to marry Keith Urban when he surprised her with an ''intense'' motorbike trip on her 38th birthday.

The 'Big Little Lies' star met the country singer in early 2005 and as their relationship grew stronger, the 51-year-old musician won the actress over completely with a romantic gesture.

In an interview with People magazine, she said: ''It was my [38th] birthday, and he stood outside with gardenias at 5 a.m. on my stoop in New York. That is when I went, 'This is the man I hope I get to marry.'''

The 'Destroyer' star was then swept away on a motorbike by the 'Fighter' hitmaker took her to Woodstock in New York, the site of the 1969 music festival, and she knew he was the man for her.

She said: ''It was pretty intense, I believed by that point he was the love of my life. Maybe that's because I am deeply romantic, or I'm an actress, or I have strong faith as well, but I just believed, 'Oh, OK, here he is.'''

The two married a year later and have two daughters, Faith, eight, and 10-year-old Sunday, and Keith praised the 'Big Little Lies' producer and actress for her role as a mother and a wife.

He said: ''I could sum up Nic as a wife, mother and human being in three words: She's all heart!''

The couple spent Christmas with a ''big crowd'' in Nicole's native Australia and had a great time catching up with the 'Aquaman' star's extended family.

She previously said: ''We usually go to Sydney for Christmas. My mother lives there, but as I live in America and my sister lives in Singapore, Momma needs us to go back regularly. It's a big crowd.''