Three is a Magic Number

"To some three is a crowd. To me, it’s a threesome."
To numerologist three is the number of a relationship. There is me, you and, the third, us. To the Chemical Buddha, three was the minimum needed to have a good time. He would also agree that it was the number of a relationship as in the number to have in a relationship. The most sacred version of the number three being two females and The Chemical Buddha. Of course, there was no way TCB could come close to satisfying one woman, let alone two women. But he always hoped they would please each other and he could watch as he drifted off to sleep.
Have you ever prejudged your potential partner? What was the impact? Did they surprise you or live up (or down) to your expectations?
What are the minimum things you require in a relationship?
What are the little extras you can bring to make your relationships last?