Each person is responsible for his or her own happiness, so do not feel an obligation to put a bright smile on the face of a notorious sourpuss. Some people are happier when they have something to complain about: you can't cheer up someone who wants to be miserable. Stick to your optimism and your happier outlook. You have things in the right perspective: don't let a naysayer tell you there's no such thing as a happy ending.