What is an example of irony in The Crucible Act 4?

I think that one of the most interesting elements of the
closing act to Miller's drama is that the relationship between Proctor and Elizabeth is
actually better once he makes the commitment to die.  It seems that their strength as
husband and wife is only enhanced when he commits himself to dying and she stands for
his decision.  When he speaks to her about being strong and not shedding a tear for him
along with the importance of his name, it is a moment where it is evident that he has
assumed a moral stature where he has become more than a man.  He towers in moral
strength and ethical austerity. It is here where their marriage is absolutely the
strongest.  It is also a point where he is going to die, and they will no longer be able
to be with one another.  This collision is ironic, for the entirety of the play had seen
them endure a fragmented notion of relationship, one fraught with hidden doubts and
accusations and a lack of complete totality.  Yet, this is not what is seen in Act IV,
where Proctor is going to die and for this, there is irony present.  When Elizabeth
refuses to take his "goodness" from him, it is a statement of ironic proportions because
his goodness can only be present with his own death and their marriage showing strength
is only evident when he dies.