Prepare for the Worst, Plan on Catastrophe?

I'm not sure who decided that it was a good idea for people the live as if the worst possible outcome is the most likely. When it comes to planning for the future, or even living in the present, I prefer to believe that things work out for the best. Especially when it comes to other people and my relationships. I tend to see the best in people, or at least I try (my current occupation is hardening me to this, but that is another issue all together). Perhaps its naive, but I never assume that relationships are naturally headed for disappointment. Isn't part of the enjoyment of life and love the hope for happily-ever-after? Now I understand the rationale that I need to protect myself and be careful about getting wrapped up in my emotions, but I never want to be so guarded that I fail to love simply because I'm scared that it might end in heartache. I like taking chances, being spontaneous. In relationships I need someone who will take risks with me. "Why not go out on a limb, that's where all the fruit is," according to Mark Twain. The limb may or may not break, but how will I know if I never try? If it holds, maybe I'll get my hands on the sweetest fruit.