I really believe this is important! This isn't about trusting that the kids will believe that you love one another, no matter what. No, the kids have to see that you actually love your spouse, that you take care of your spouse, that you speak gently to one another, and that you take care of one another.
It can for sure feed terror in the hearts of kids when their parents fight, especially as they also hear about how any parents divorce and walk seperate ways. Many kids think of a divorce as one of the worst things that can happen in the world, and thus, they are really scared that it might actually happen to them.
So, once again - love your spouse, and let your kids see that you love one another!