Candles and bubble baths. Go for a long walk at midnight. Make long, slow, passionate love. Write poetry for each other. Kiss and smell their hair.
Hugs are the universal medicine.
Give random gifts of flowers,candy,poetry etc. Tell them that their the only one you ever want. Spend every second possible together. Tell them that they don't have to do anything they don't want to and mean it. Spend some time looking into each other's eyes.