Be open and affectionate, treat her well, buy her thoughtful gifts (they don't have to be expensive, just things she will appreciate). Listen to what she talks about and take an interest in what interests her. Share what interests you with her. Don't crowd her or be jealous about what she does when she is not with you. Hug her and hold her hand. Organise a special treat - for example surprise her witha day out to somewhere special or exciting. By the way after two years maybe it is time to tell her you love her.