What explanation does Mr. Hooper give Elizabeth as to why he won't remove his veil?

When Elizabeth, Mr. Hooper's fiancee, asks him to remove the veil and explain to her why he put it on in the first place, he responds that he cannot.  When he refuses to remove the veil, she presses him to at least explain himself, to "remove the mystery from his words".  The minister says only that he has vowed to wear the veil forever, as "a type and symbol", and as she receives his explanation, Elizabeth is suddenly stricken with a sense of the symbolic horror of his act.  By refusing to let go of the black veil, Mr. Hooper is in essence displaying his willingness to give up even the most precious of human relationships, a relationship of love.

Mr. Hooper's black veil is symbolic of the masks all men wear to hide their innermost secrets and desires.  Just as the veil has the power to destroy the sacred relationship he might have had with his fiancee, so do the masks that all men wear have the potential to ruin their relationships with those around them in their lives.