My Dad taught me (by example) to do that. I'm quite sure they must have disagreed sometime, but I never witnessed my parents exchanging bitter, angry or insulting words.
I hope that, maybe, I learned something from them.
I tell my wife that I love her all of the time. I also tell that to my kids. I always knew it from my parents, but they never said it until I was older.
My wife and I also fight. Not a lot. But we dont hide our disagreements. This is intentional. We want our kids to know that two people that love each other CAN disagree. We also want them to know that when someone gets mad, it doesnt mean the world is going to fall apart forever.
If the path were just a straight line of agreement life would really suck.