I'm not married, but being a man, i can tell you how most men think. Once a man is married, he immediately assume the position as the head of the family. I'm assuming that you've been married for some time now, right?
Well, if so, then it's exactly it. The man is frustrated that life hasn't turned out exactly how he imagined it to be. Now before you start thinking too much about it, please read all of it. For what he imagined there are two reasons for which it is his fault:
1. He didn't share the image. You can't expect somebody to just read your mind so easily when it comes to dreams and life expectancies
2. The life he wanted demanded certain attitude changes, things that aren't so convenient for him. Sacrifice after an age is very hard to achieve.
Other reasons vary from being stressed and frustrated with his life that he takes it out on the one person who he thinks can take it, to simply being angry at you for a reason or another.
I hope you didn't feel offended by any of this. I'm just talking from the experience of others that i have learned to observe. That and the fact that the men in my family are rather grumpy and like that.