"I'm sorry"s and "Thank you"s are as important as "I love you"s. Both show that you don't take each other for granted.
What I've learned so far: To live happily ever after is a choice you make, not a destination marked by a fairy tale wedding. It is a journey, and it begins with you, with an open heart and an open mind. The presence of (an)other person(s) is to share, and to add color and flavor to what you already have.
Trust should not come from knowing (or hoping) the other will never disappoint you, but rather from your own strength in building the courage within you so that you TRUST yourself to be able to make everything ok, no matter what happens.
We're not like two pieces of puzzle that fit perfectly. In order to function perfectly, we each need to be whole as an individual. That way one can give freely to the other and to others, like an overflowing cup.