Tom says something at the funeral, he remembers that- he has to, Rebecca is his wife- but not much else. She would chide him for forgetting what he said, but lovingly so.
"The last words you'll ever say to me, and you forget them? For someone supposedly so smart, you're always so scatterbrained," she'd say before tapping the side of his head.
Rebecca would be wrong, though. Because he never really stops talking to her. Tom can't raise their sons without her.
Later, Tom gets a reputation for being so good with his words. He had one in his old life, too. He remembers smiling whenever he'd read course reviews praising his lectures. He loved lecturing.
But there's this little bubble where his words don't work anymore. And this bubble, Rebecca's death, is when he needs his words most, to comfort his sons. To comfort himself.