My H tried to explain to me why he had a ONS and it made me feel better for all of two seconds. Knowing why didn't take away any of the pain or any of the fear. I am still questioning why even though he has told me over and over. I think knowing why has made me question everything I ever did when it happened. If only I had done or said such and such it wouldn't have happened. It is making me live more in the past than I should be.
Time is the only thing that will take away the pain and fear. I think asking why will just stir up too much pain and may make him want to distance himself from you.