No matter how much you love a person just expect less from them. Because the moment you want more is the moment you demand for everything that person has.
Remember one thing, the person you love does not only focus on you. He/she has his/her own life. he/she got a family, got a brother, got a sister, got best friends or friends and so on.
You are part of his/her life but not entirely his life so give your love without expecting or demanding more from the person you love.