I suspect your wife wasn’t paying attention when the explanation for the delay was given. These days there would be a riot if you sat there for hours with no explanation. Maybe she had her earbuds in. Even when the captain isn’t being very forthcoming, eventually enough people start bugging the stews that the stews start bugging the captain to say something.
At a massive airport like DFW the delays can easily extend hours or even all day after the weather moves through. If there’s storms or fog in the morning they will shut down the airport until they pass. They probably land 2 or 3 planes a minute on average at DFW so a 2 or 3 hour weather event can effect hundreds of planes from all over the country along with some mid-way over the oceans. When they reopen the airport they can’t let all those planes arrive at once so they space them out and start assigning takeoff times to everyone, often hours beyond departure time. The airport can still only handle the same arrival rate as normal and now they’re trying to mix in all those delayed flights sitting on the ground everywhere with the normal scheduled ones too. I have no idea if that was the case that day but that’s how it often goes.