I wonder why couples have so many difficulties. It's an incredible gift to find your partner, someone who loves you as you are, with your gifts and quirks, who is your champion and will help you be your best self. It's actually easy to keep communication open, honest and have integrity in your relationship. You did it in the beginning. Yet it is hard, too.
Part of communication is what you say; a huge amount is HOW you say it (For example, "When _____ happened I felt ____. I wish _____." is completely different than, "You asshole, you did _____ to me. I'm so mad I don't want to listen to a word you have to say," and storming off.)
Part of doing well together is what you focus on in your relationship (all that's going well vs the one or two things that aren't. John Gottman of the Love Lab in Seattle who has been studying couples for decades says you need a 5:1 ratio of good to poor interactions to stay happily married.)
I've been walking my dog every day. He's a 10lb. Papillon. I see hairy 100lb dogs, labs, terriers, mutts, goldens, pugs, bulldogs, etc. They're all dogs; yet in so many shapes and sizes. Just like people. You're both humans, yet your lives were different growing up. You came from a home where your parents yelled--or not. You came from a family where affection and kind words were spoken and an occasional disagreement or argument was repaired quickly and you saw it--or not.
Whatever you grew up with is "normal" whether it was healthy or not. You created coping strategies as a kid for your particular family. Good for you. You needed those. But now you're an adult and you get to recreate strategies that work for you as an adult in a primary relationship. You get to question your coping strategies.
Maybe you didn't learn how to express feelings--or even to recognize what you're feeling. If so, you're in the same boat as most adults and can learn now.
Maybe people in your family didn't make eye contact when talking; you can do that now. Maybe you got a blank expression from your parents (called Stillface); it hurt you even if you don't know it and you have an opportunity to live differently now.
Make your marriage your top priority, even above your kids (just a little bit) so you can provide a safe environment for them. Have each others' backs. Make sure your partner is the first person you go to with good news or disaster. Play, laugh, hang out, do what you did when first dating.
Take care of your issues kindly. Don't sweep them under the rug.
Focus on the good. There's a lot there.