So the second honeymoon is over. It was bound to happen eventually. Mama is right to tell you not to beat yourself up.
Anyway, you're wrong about not having changed. In the past would your W have directly called you on it? Or would you have calmly listened to what she had to say?
You have every right to be unhappy and moody sometimes. Just don't let it dominate your life. You and your W have to learn to accept that occasionally we all just have an off day and are out and out grumps.
The bad days come with the good. In M you don't just get to pick the good days.