explain why mr.hale's comment here is both ironic and ignorant

The fact that a man has been killed over what seem to be "trifles" shows that Mr. Hale is completely ignorant about woman and how the react to certain situations. It is an ironic statement because the murder is hardly a trifle; it is something bigger than that and goes beyond a trifle. If it was truly a trifle, a murder would not have occurred.