Distance
I had been married - second time - for five years when I was deployed to Iraq for a year.
Two years after I was back I went to Germany for a year, that turned into two years.
R&R from Iraq took place in Ireland, a country my wife had always wanted to visit. I was able to make a number of short personal or professional trips back to the US from Germany, and my boss always allowed a couple days over weekends to/from on the temporary duty trips (Helped living close to Atlanta).
I've been happily married this time far longer than the happiness lasted the first time. I tell people "I'm married to someone who likes me, and it only gets better from there."
My advice? Real/genuine communication rather than superficial platitudes. "What do you think about...?" "Please explain how X works..."
A team of equal partners who decide how to share responsibilities is well on the way to success.
I remember pre-return training the first time I was deployed overseas in the '80s. The basic substance was "your wife ran the house just fine for six months while you were gone; don't go home and try to tell her what to do." If you are going to be on the road a lot, see if she's willing to be the check writer/etc. for the family.
If you want to read, I like the advice above to read on the road. You could get two copies of a book and read to each other, or discuss the content.
Too many hours of "hi honey, love you, miss you, honest, cat pooped in the garden, need stamps, gotta go, bye" is not good.
Priorities for flying: aviate, navigate, communicate. Relationship: communicate. repeat.
Good luck!
PS My wife has no interest in flying an airplane. Our first date, though, was a ride in a 152. She's happily flown in singles, twins, and gliders with me. I'm an incredibly lucky guy!