"Well, if you're trying to memorize potion formulas," Kate said, pausing in the doorway, "you certainly aren't doing it the way I've ever seen an adult potioneer do it. I've seen students trying to memorize, but graduate potions makers? No. Robert would tell you that you learn by doing. That's why you had a lab in potions class.
"If you want to learn them without the books, make them. Any cook will tell you that if you make a recipe enough, you don't need to look it up anymore. But if you want to make it harder than it has to be, then you're certainly welcome to."
She went up to her room and found Robert busy reading and studying and doing research of his own. She got out her coat. He looked at Kate, uneasy about the idea that she would go out by herself.
"You worry too much, Old Man," she said softly. "I won't be long. If I plan to be more than an hour or two, I'll let you know." She put her coat on. "Robert, I'm going to ask you one more time. I'd much rather share any curse with you than to continue to live my life without you. Don't shut me away from you so much."
He looked at her trying not to be sad about it, but he couldn't touch the ones he loved the most, not even her. He couldn't hold her hand, couldn't stroke her hair, couldn't kiss her. Couldn't read to his grandchildren, couldn't do the things that meant the most to him. At times it was tempting, and he wanted to simply take the risk to avoid being alone and isolated. But he looked at her, remembering how very much he loved her, more than himself, and he shook his head. He couldn't risk it.
"Alright," she sighed. "Please consider changing your mind. I'll be back." She apparated out.