Make thoughtful gestures.
Let your partner know you think of her even when she's not around, and that you really care about the details of her life. Does your significant other have an important presentation to make to a new client? Send an encouraging "good luck" text message before the meeting, and remember to ask how things went at the end of the day. Is he or she worried about an ailing family member? Show your concern and empathy for what your other half's going through.
You can also strengthen your relationship by taking time to get to know what makes your partner happy and show that you care with thoughtful little gifts and gestures. Pick up her favorite flowers occasionally; bring home his favorite snacks from the grocery store; or make a reservation at a favorite restaurant or a tee time for a round of golf. Thinking warm thoughts when you're apart can easily turn into warmer thoughts when you're together.