Kate's parents had this mantra that if they ever had an argument they would agree to hang in there and resolve it, and never go to bed angry. In her own marriage, Kate has tried a few times with mixed results to follow in her parents footsteps. A couple of times her husband refused to talk and simply went and slept on the couch, much to Kate's dismay. Other times, they were able to work through it (albeit late at night), and more or less comfortably go to bed together.
One intent behind Kate's parents' common folk-maxim is a good one—namely, that you make the commitment to work things out, rather than stomping off and making little real effort to put things to rest. On the other hand, pushing for some resolution, especially late at night, is often like the psychological equivalent of trying to defy gravity.
The problem is our brains. When we get angry the reasonable parts of our brains—the prefrontal lobes in the front—shut down and the all the action moves the back where our reptilian brain takes over. We get the fight or flight response, we get tunnel vision. We want to make our point and get the other guy, damn it, to understand what we're saying. In our quest we might throw in Christmas 2008, your mother, and that time you got drunk at the 4th of July picnic—it can quickly get ugly. The real problem at this point is not what you're actually talking about but the emotional fire in the room; you really can't solve the problem until the fire dies down.
And this can take a while depending on how worked up everyone gets. For men it's even harder—it can take them physiologically three times longer to cool than women. If you start all this at 10 p.m., sanity won't be kicking in, at least for him, until Tuesday morning, maybe.
What you do want to do with all this is be responsible with your emotions. Do what you need to do to skip the dig at Christmas '08 and put out the fire calm yourself down, by taking a walk or by sitting in the bathroom and doing some deep breathing for awhile. When you're back into your prefrontal lobes, your blood pressure is down, and the tunnel vision has expanded, then sincerely try and solve the problem. The means listening and talking it through, not the quick I'm sorry, pseudo-hug in the kitchen, and sweeping it all under the rug.
So what does this mean for Kate? If she and her husband are able to settle fairly quickly and talk productively, go for it. If not, and it's 2 a.m., the prefrontal lobes are likely done for the night. One of them might need to head for couch but say I'm still upset, am going to sleep here, but in the morning after I feel better I want to try this coversation again.
Then do it.