The 46-year-old actress talked about her love life in a new interview with InStyle magazine.
"For every single night he's away, he leaves me a love letter. Every single night of our relationship," Kidman said.
The actress tries to keep the long-distance to a minimum by joining him on tours.
"That's basically how I've seen most of America, on that bus. Keith and I are both gypsies at heart. We can make our home wherever we are. The girls are like that too now, so we take them everywhere," she said.
Kidman says she always tries to overcome her fears.
"I always try to push through fear. I won't be crippled by it. People say 'Oh you take such risks,' or 'You're brave.' And I'm like 'Well, if you only knew-inside I'm really frightened!," she said.