Throughout life we often experience new people come into our lives and then leave.  They may leave for all sorts of reasons, maybe the ending is abrupt or maybe things have come to a very natural end, it has ended in a way that was meant to happen, things have run their course.  Whatever the reason it is natural to feel a whole range of emotions, upset, sadness, anger, maybe even relief, you may miss them with all your heart but deep down you knew that they were not meant to be with you forever, no matter how much you had hoped.  I believe that it is very important to experience and allow those emotions to flow, it is all very much part of the life experience and the process of healing.  When the time is right you will reflect and realise that even though things may not have  been easy, there will be a silver lining somewhere.  The person will have left you with something valuable, maybe they helped you to become the person you were meant to be, maybe you have learnt something valuable about yourself, you learnt how not to be.  They were there for a reason that you needed them to be.  No matter what the reason for them being apart of your life,  give yourself time to experience the emotions of them leaving and then let them go and take away with you all the positives in the situation and forget the negatives (if there were any)..