Treat the relationship as a friendship first. Avoid letting the camouflage of romance blur your vision. Ask yourself how you would respond to a friend in the same situation. Don't put on airs. If you've had a bad day, don't pretend otherwise.
Nobody is happy all the time.
You want a friend who can accept you as you are. Do things for yourself sometimes. Don't be afraid to be alone. Don't be afraid to argue. Arguing, although frightening, can clarify issues and develop a closeness through understanding.