One of the problems with OCD suffers is trying to convey their thoughts to a loved one (like a parent, spouse, boy/girlfriend, etc.) who does not have OCD.  When the sufferer tries to talk about their OCD thoughts, the loved ones usually doesn’t understand their problems.  OCD makes no sense to them.  From the sufferer point of view, their thinking makes total sense, but from the non-sufferer point of the view the OCD thinking makes no sense.

Here is my reasoning.  The reason non-sufferers don’t understand OCD is because they are trying to use logic to understand OCD.  By definition, the OCD thoughts are irrational.  You cannot use logic to understand the irrational.  If the thoughts were rational then you can use logic to figure it out.  But OCD thoughts are irrational and by definition has no logic.