Everybody's life looks great from the outside looking in. But live it and you'd probably tell a different story. Rich people, married people, single people, etc., do not necessarily have it better than you do; they have it differently.
You have it also. You just have to figure out what "it" is, then work hard to develop it. When you are clear about what you have and you're working on that, you'll love your own life and won't covet theirs.