40 years for my wife and I.
I've learned two things that I believe are mandatory,
Love Christ more than you love your wife.
Love your wife more than you love yourself.
If you do these two things I doubt you will have any problem you and your wife can't overcome.
A third bit of advise that is optional but highly recommended...
Spend the extra money and hire a qualified contractor to do the kitchen remodel rather than doing it yourself. (I've not taken my own advise twice now, there won't be a third time)