Bell, 39, spoke with actor Justin Long on the "Life is Short with Justin Long" podcast about a recent yelling match with Shepard, 45, over her request for him to do some chores to help around the house.
"In fact, we had this pretty incredible fight recently,'' she said. "Incredible. I mean like top of the lungs screaming.
"We both blacked out and got into a fight and I don’t actually remember what happened, but what transpired was a lot of volume, a lot of harsh words being thrown around, and it was an angry, angry fight about how nobody does anything for anybody else. I grabbed my pillow and stomped down the hall, and I sleep in the front room and I’m crying. And we don’t talk for three days."
It was sparked by Bell's request for Shepard to do a few chores on a Sunday to help while she was gone.
"It was about things around the house that I felt I needed help with,'' she said. "We have a relationship where you are supposed to be able to say, 'I need your help with this.'
"I left a note and I was like, 'Hey dad! Would you mind taking the two towels in the dryer and folding them,’ and then like one other thing. I thought, 'That’s 10 minutes of work.' At that point, the house was getting to be a lot for me. The keeping up with the mom stuff, the shoes being outgrown, I'm the one ordering that, whatever."
Shepard, who has two daughters with Bell, later expressed his displeasure over the request.
"He goes, ‘When you leave me notes, I feel really controlled,’ and he launched into how he felt about it,'' she said.
Once the yelling subsided, Bell tried to find a solution.
"And I said, ‘OK, I totally hear you. It will never happen again. If I need something to be done around the house what is a way that I can do it, that you’d be OK with hearing? What's a better way I could do it?'''
The way Bell sees it, the occasional spat can be a good thing for a relationship as long as there are rules for what lines can't be crossed in an argument.
"We're really good fighters,'' she said. "You should fight with your partner. I don't think you need to be a carbon copy of anyone else, but you do need to know the rules.
"Once you know those things and you know how to responsibly disagree with someone, I find life gets a whole bunch more interesting because you're keeping your side of the street clean, you're not losing yourself, you're allowed to say what you need, but you don't have the guilt or remorse or regret about it later. And your skin gets a little thicker."
Bell and Shepard have worked to be completely honest with one another in their marriage.
"We have thin skin outside with people in the world, but not with each other,'' she said. "We can be very candid with one another."
They also want others to know that their marriage isn't always perfect.
"Something happened with Dax and I early on where we decided we were never going to not be asked about our relationship," she said. "So if we were going to talk about it, let’s make sure we show the good, the bad and the ugly and how we handle it. Let’s not make it saccharine, and we really try hard to not make it saccharine, and we talk about the fact that we do fight, we do go to therapy, we dislike each other a lot sometimes."