I think it would take a lot to lose my trust in a friend. We all make mistakes, and that's where forgiveness comes in to play. If I were to lose my trust for someone based on one act of mistrust, what kind of friend would I be? I wouldn't want that to be done to me! We are not a perfect race, we all make mistakes and mess up. It just depends on how we are willing to react after that choice, are we apologetic and do we feel bad for doing so? If so, I think it is the obligation, duty, and requirement of the other party to forgive and start to build that trust back up.
Great question Midg!