Well, for one misunderstandings can occur due to lack of proper communication.

the rest of the reasons beat me

You'll find that there are misunderstandings every day in our life, the ones we know about and the ones we don't.

Each of us has experiences.  All experiences are handled by what we know at the time.  So our lives become a serious of experiences and they are coloured by our understanding of life and its challenges.  

We discussed this somewhat last night...suppose there are major changes happening in your life...you are on the threshhold to new and innovative adventures.  These adventures seem to change who you are from your focus to the inner core.  Young people tend to rush into the next step and/or look back and mourn what they were in their last adventure, instead of moving forward.  Older people have learned...let life unfold!  That is the key to balance in all things.

Misunderstandings arise from our understanding of all things and how it colours who we are as we approach each and every experience our life contains.