Marriage Basics
You learned about marriage from your parents, which means that you were in "basic training" from the moment you were born.
All of your senses were aware of what was going on around you, what was said and done, what was felt in the air, what was heard and what was not heard.  At first, you accepted "what is" as the norm and what should be.  This is normal, this is right. This is the way marriage is.  Period.  
As you grew and saw other people, families and relationships, you broadened your perspective to other ways of relating in marriage.  What you saw was at times very different from what you experienced at home.
Some families did family time one way, some did another.  Some parents spent more time together, some less.  Some Shabbat tables looked one way, some totally different.  You gathered it all in and made an unofficial list in your  head of  "when I get married, I want it this way."
You read books.  And watched movies (good marriage = "happily ever after", right?). And listened to love songs. And read poetry. And…
Then you really knew that your family didn't do it right and that you'll have a different marriage.  Yours will be great.
And one day, you fell in love.  You finally had the story and the song and the poem.  It was perfect.  It was right.  Ahh… so wonderful to fall in love.  "I’m so lucky."
One day, life kicked in.  And the boss was in a bad mood.  And the car was in the garage and the bus was late.  And the cheese in the fridge went bad just as you were about to make lasagna for supper.  And why was the utility bill so high?  And both parents wanted us to come for Shabbat.
One day, your dearly beloved was explaining to you very passionately why… No, he wasn't  yelling, he was just expressing himself so that you'd understand.  But you thought he was yelling and then, instead of calmly discussing the issue at hand, you were yelling about why he was yelling (or not).  And you wanted to cry.
What happened?
What happened  was real life, not books, movies, songs or poetry.
What happened was basically what eventually happens in every marriage, with varying story lines.
The question isn't "what happened?", rather "what can I do?"
It isn't about having a good marriage, it's about what needs to be done to have a good marriage.   You'll have a good marriage when you do what needs to be done in order to have a good marriage.  There's a lot of personal proactivity in having a good marriage. It's about learning how you can create the dynamic that will bring about a thriving marriage.  There are principles to incorporate; there are tools to learn and to practice.
 
It doesn’t mean that something was inherently wrong.  It doesn't mean that you didn't know the person you married.  It doesn't mean you made a bad mistake.  It just means that after your childhood and all the years since, it's finally time to learn marriage basics!