Well, considering I feel I've found my "soul-mate" I have to say yes, there is such a thing. But, there can also be "matey's" in my book, so if something were to ever happen to my dh - and he feels the same - we probably will love again, but both of us know that it will never be the same as what we have - neither of us have experienced this before although we've both been married before and had other "relationships". There's a bond there that seems to transpire both time & space. We "feel" each other even when the others miles away - its hard to explain. Just a connection that we know goes across so many levels.
As far as predestination & fate - who knows? As Little Toe said maybe couch potatoes were destined to be just that. Perhaps it's fate that brings us to the choices we make in life, the turns that we take that we never imagined. We're all on this planet, evolving, learning & growing. Some religions believe there's a good reason for that - that we're here to learn specific lessons at a specific time, and then to be reincarnated to learn even more, until we get to the point of complete consciousness & can go on to the next level. Whether they're right or not we'll never know - at least not in this lifetime - at least not most of us!