We argue about something about 2-3 times a year. It's usually me taking umbrage at something inconsiderate that he does. When I look back on it, I don't think he intends to be inconsiderate. We're both used to having our own way, got married very late, never lived with another person in a romantic relationship, etc., so he has some learning to do about little things. I don't think it occurs to him. Also, he's very close to his family, esp. his mom, and I've noticed that he tends to favor her a bit--I don't think he realizes that when you're married, the spouse usually comes first (he lived with his parents sometimes in his adult life, to lessen his commute to work, for example, again, he's used to living with THEM, not a spouse/girlfriend). He's learning, though--only because I argue with him over it
It used to be money. When we met, he had a TON of debt for silly things; I am a compulsive saver, and much more money-savvy. After a few arguements about his fiscal irresponsibilty, we got the idea! He's greatly improved; I tried to set a good example for him. I think he realized that he had to grow up, and think about boring things like mortgages, etc. No more "toys". He's since paid off a lot of his debt, and I'm always in the background, reining him in a bit when he asks for advice.
We always make up, and I make a point of discussing what's wrong when the tempers cool down. (I shout; he retreats into silence when we "argue".)
He's a very good, decent man; he just has to get used to a long-term, living together situation. He's very loving and caring. If what he does is the worst thing he ever does, I can deal with it!