This has to depend on whether you believe in fate or whether everything is just a load of random events. Wherever you go you will meet someone special or be special to someone else. I like to believe it's fate as it has happened to me, but I suppose a professor of human behaviour would claim the chance of meeting someone that could change your life is very likely.
By changing your life I don't necessarily mean a partner. It could be another woman/man who influences you to be the best you can be without knowing they are doing it. I met a man who was 20 years older than me, who played a great part in my life after my father died, purely by accident. Simon Baker as The Mentalist reminds me of him so much. So, to answer your question, I believe it's a bit of both.