Like most on the this thread in long marriages (25 years plus for us) we have argued less the longer we have been married. We are more considerate, kind and appreciate of each other as the years have gone on. As a PP said, we thank each other for the things we do, even if it is 'expected' - the meal, the washing, emptying the bin.
When we do disagree, we always play the ball, not the person - we have never called each other horrid names or been cruel or said anything nasty - I think that is abuse, myself.
We tend to make up before bedtime, mainly because I am such a chilly soul and DH generates heat, I have to clamp myself to him in bed to get warm, which rather weakens your hand in a fight! I don't know - I think basically we both really want to make each other happy and to get along, so we try to be reasonable with each other.
It is definitely easier now we aren't in the white heat of a young family and have more disposable income, this is a lovely chapter in the unfinished story of our marriage.