The key to any good marriage is definitely good communication. It's feeling comfortable telling your partner what you're really thinking and being ok with listening to how they feel as well. In an open marriage - it's absolutely critical.
We communicate exceptionally well in our relationship. I can tell my husband anything - if I'm irritated by something he's done or has said, I know how to talk to him about it without him feeling attacked. And we both know how to listen without getting worked up and defensive.
We rarely argue, and never have what I think of as fights - no yelling, no being mad for days on end. One of the perks of having an open marriage is that you communicate like crazy - all the time, about everything. Taking the first baby steps into everything we've done has meant endless conversations, mulling over the what ifs before, analyzing the issues after an encounter, etc. Lots and lots of talking.
We're very adept at talking about our thoughts and feelings, even ones that might upset the other, without misunderstanding, judging, and pain. We really hear each other, and know that we care for each other so deeply that even when we disagree, we know we'll find a compromise, so things don't get heated.
In a nutshell - I think my husband is an awesome guy, and he thinks I'm just as great too. So even if I do or say something he doesn't like or agree with, at the core of the issue, he loves me and doesn't think I'm a jerk or a bad person. He gives me the benefit of the doubt. I do the same for him. Because I love him. And if he were really a jerk, I wouldn't love him, and wouldn't be married to him. You'd think that would be obvious, right? But many couples stay in marriages when it's clear they barely like their partner at all.
Sometimes I'll be in a bad mood and I know he's thinking, "Why is she being such a bitch?" or he's cranky and I'm thinking, "He's being an ass!" But we both recognize that this is not our norm. I am not a bitch and he is not an asshole. We have our moments, but we recognize those for what they are - moments. You're not going to adore your partner 100% of the time. But if you don't have that underlying love and respect, I think that's a big problem.
When we do have our moments, we've learned that the person in the better mood should back off and waits until there's a better time to have the discussion. At the same time, the happier person will look to see if they can help make the other person feel better - volunteering to take on a task the other has on their plate, taking over the bedtime routine and running a bath for the other, etc. No poking angry bears in our house - we give each other a wider berth and the benefit of the doubt when one of us is having a particularly cranky moment. We're well matched in this respect - some couples we know have one of them playing the martyr role all the time. They're perpetually moody or grumpy or complaining. When you live with that frequently, I imagine it's much harder to want to help your partner get out of that place.
I'm always surprised when I talk to friends and they have no idea what their partner is thinking about things - aren't they talking? Often not.
How well do you communicate in your marriage?