I tell my wife of 25 years, "I love you", each night before sleep. I do it because if I die in my sleep, that's the last words out of my mouth I want her to hear and remember.
I give her a kiss each time before I leave the house because, if I die while gone, that's the last thing I want her to remember me doing. Even if she's still sleeping when I get up and go to work, I kiss her in her sleep. She knows I did.
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.
Those thoughts cross my mind on occassions as well. Your wife is a very lucky woman.