Here's a great quote "I think more people would still be married if they realize that better comes after the worse."
That's why she needs to fight it out with you and work on this. Because (as childish as it may sound) you didn't make this promise alone.
Life is freaking hard. Why should marriage be any different when it's really the biggest part of your life along with children? People who say "It should be this hard, it should be this much work" are cowards. There are days when it's effortless.....there are more days when it's effort.