Cox told Life magazine they just really like each other.
"He gets a kick out of me, and I get a kick out of him. We're a good balance for each other," she said.
"He likes the fact that I'm so gregarious -- although it can also make him very uncomfortable -- and I like the fact that he is so sensitive," she said. "We're a great team."
On a recent vacation to Sardinia, the couple got into a row over "stupid stuff," she said. They saw a therapist later who explained what was happening between them.
The therapist said David is more private and doesn't like to fight in public.
"I don't scream," Cox said, "but I have no problem saying what I'm feeling in the moment. David's the opposite."
She said she's learned she needs to take him aside to explain her feelings.
"But I could see how relationships break up if you don't go, 'What are we doing!?'" Cox said.