You don't have a clear read on the past, and that leads to a confused sense of what the future might bring. You may build up an old romance in your head to be much bigger and more profound than it really was, and then spend too much time looking for a love affair in the present that can live up to (read: mimic) that old one -- and all the while, the old one was just, well, not as special as you remember it to be. If you build up the past in your imagination and try to recreate it in the present, you run the risk of overlooking great opportunities that pop up right in front of you.
After all, even if that old relationship was as great as you remember it, it's over now. You can't go back in time, and you can't conjure up a person or an emotional connection that no longer has anything to do with your current life. Instead, shift your focus firmly onto the present and the future. Your big challenge now is to learn to see and accept what you've got and to look forward to the unknown that lies ahead, rather than pining away for something that can never be again -- and that maybe never even existed in the first place.