Happy relationships?

How to tell if your relashionship with someone is good? I think most people can do it pretty easily (though who knows…) I have a very vague picture of it. I understand very well that I will never be in this happy-yogurt-ads kind of relationships. When the mother is beautiful and kind and the father is strong and everything lit with the sunlight and everyone is smiling. I won’t be there. For the simple reason that I’m myself is not like that. So, how can I be sure that I’m happy if I’ve never actually been happy? I’m used to all sorts of suffering, rejection and dissapointment. When I feel something remotly resembling joy or happines, I genuinely feel a bit scared. As if it’s a new symptom I’ve never experienced before, as if I have a new kind of pain in my body and am scared what kind of a desease might cause it. The best thing I can do now is to try to analyze what I feel and to get used to the good feelings and to change the situation so that I would have more of them.