One word... Communication.

Its very easy to write off, but most couples now don't ever actually resolve issues. Communication doesn't mean just talking as much as understanding and being able to work through issues and such. For the first couple years that my wife and I were married, we "communicated", but then we had to learn how to actually communicate. We never really resolved many problems but just pushed them off and it starting making a distance between us. It takes work for sure and you have to both be willing to work at it.

Good luck man. Also, don't be afraid to try counseling and/or a marriage retreat or similar. I've not really been to one but a couple buddies of mine went to a couple of them very early on in their marriage (<2 years in), and they have spoken extremely highly of it. They aren't just for "couples with problems" but moreso for "couples wanting to work to prevent problems and grow closer together".

I hope everything works out for you guys!