Now I remember. Moreover, I think you might have incidentally solved it. I believe it's one of "red herings" throughout the story.
Spoiler:"Till death do us part", right? So the first impression is that his wife had died. But actually, as we don't find out until very late, it's Max who's fighting against death (he even almost surrender - after he falls down the chimney into his "home"), hence the skull. So death really endangered their marriage, but in exactly opposite sense than it was initially suggested.
