Truly KNOWING your partner is incredibly important to a healthy relationship. Not just knowing what they like and what they don't like, but also knowing WHY! You and your partner change every singe day of your lives so maintaining daily connection is critical to changing together, instead of changing separately. When you change and connect, it doesn't feel like change!
Here is a great site you can use regularly when you're just hanging out to stay in touch with one another...
You can also read Gottman's, The Seven Principles of Making Marriage Work
Mary Bowles, MA, LMFT, RRT, MIAAN