She said: "It made it better, because there's no way out. Well, there is, but it's not one you want to entertain very often. In an argument, I just say, okay, don't turn into a rapid pit bull so much any more."
While she is blissfully happy with Harrison, Calista - who adopted nine-year-old son Liam just a year before meeting the Hollywood star in 2002 - admitted she was initially wary about their relationship because of their 22-year age gap.
The 46-year-old actress told Sunday Times Style magazine: "I thought, 'This is ridiculous, he's way too old for me, I'm way to young.' But you can't help who you fall in love with and I fell in love with him. It might be an issue in the future, but, as of now, it really hasn't been.
"I like to tease him about it. I use it against him. He's lived a very long time, you know. He knows everything. I say, 'Yes, honey, you're very old, we know that.' "