"You can't because you don't know how. (75)
The wife is putting her hubs down hard here, telling him he doesn't know how to speak, much less about this child. He could speak about his dead child, but certainly wouldn't know the right way, according to her. Basically, he's doomed from the get-go.
"Think of it, talk like that at such a time!" (98)
In this line, the woman reacts to what she believes is yet another instance of how her husband doesn't know how to speak. Right after digging his son's grave, the man talks about birch fences rotting. Now, we can see that rotting actually does have something to do with graves. But if we were this woman, that's definitely not talk that we'd want to hear after watching our son's grave be dug.
"You—oh, you think the talk is all. […]" (116)
The wife says this line just after her husband tells her to talk about her grief. If only it worked that way. For this lady, grief is more than just talk. It's buried deep down inside, beyond the reach of language and communication. And beyond repair.