The relationship between the two is fraught, to say the least. Things may have been fine between them in the past, but since their son tragically passed away, it's a different story entirely.
At the heart of this couple's increasingly bitter quarrels is Amy's charge that her husband has never adequately mourned for their son. The father is indignant at such a suggestion; he gets so mad at Amy that he threatens to bring her back by force if she makes good on her threat to leave:
‘If—you—do!’ She was opening the door wider.
‘Where do you mean to go? First tell me that.
I’ll follow and bring you back by force. I will!—’
There's clearly been a breakdown of communications here. The problem is that Amy and her husband have different ways of dealing with grief. There's no right or wrong here; everyone deals with grief in their own individual way, and it's the same in this case. Amy is more emotional; she wants to pour out her heart and be comforted and consoled by her husband. That he's unable to give her the comfort and the consolation that she so desperately needs is the reason why she's just about ready to head out the door.
As for Amy's husband, he's much more stoical, more matter-of-fact. His wife chides him angrily for coming into the house after he'd just buried their child and talked about "everyday concerns." She interprets his behavior as callousness, but it is simply his way of dealing with grief.