Sometimes, when you get off on the wrong foot with someone, usually the both of you would decide to "start over" or pretend that none of it ever happened. In mild cases, this is very achievable. However, when it comes to cases of emotions, trust, and the heart, starting over is always easier said than done. Starting over is very easy if you've just met the person. But when it comes to long term friendships or relationships, starting over is nearly impossible.
The simplest reason for this, and probably the easiest one to accept as well, is that you already know each other. Starting over would be impossible simply because the relationship has gone so far that it would be impractical to start from the beginning. However, in cases like these, starting over does not always mean going back to the beginning. If the hurt was a result of something like a "little white lie" then starting over means forgetting that the lie even existed. Basically, forgetting that it ever happened at all.
What happens if its something you can't forget? Can you really "start over"? More often than not, the answer is no. Sadly, these things lead to broken relationships mainly because one or both of the people in the relationship can't forget what happened. As previously mentioned, "forgive and forget" does not always come easily.
When considering starting over, you need to keep in mind that it is virtually impossible to do so in certain situations. What you can do is work together to get past what ever happened, learn to forgive and slowly forget. That way, instead of trying to change what already happened, you can change how it will affect the future.