As someone that has always traveled for work (although much more right now!) I have to say that I have felt that it is emotionally harder for the person at home. I would think that would be even truer when kids are in the picture. My reasoning has always been that while traveling on the road is stressful and physically tiring, the person at home has a huge absence to deal with and with the kids I would imagine it is even more noticeable. Obviously I know how exhausting and stressful travel can be so I am not pretending that travel is easy for us. I just bring this up as a way for you to maybe try to empathize with your wife and see if she will open up and communicate a bit more with you about how she feels. Like you said you want her to look to your harbor and that means you might have to put up with some complaining. However if she can trust that she can let her guard down with you and complain and know that you will be strong and listen without taking it too personally, it might help with the continued strengthening of your relationship.
I have to say I am still amazed at how different you "sound" when you post. There is a lot more strength and confidence in your "voice." Don't let her off days throw you off!! You are doing great!!
But what is happiness except the simple harmony between a man and the life he leads? ~Albert Camus