[There's a longer pause on John's end because Alfie does have a very valid point. But...]

Alfie, she saw my dreams, like you did. But they were... it wasn't like what you saw. It was Sherlock dying over and over, Moriarty torturing me with it. She's never breathed a word about what she saw to anyone but me. She's kept Estinien threatening her life quiet until I pried it out of her with everything short of a crowbar. She's... she's so hurt and scared...

[And that makes him want to help her. That vulnerability makes his heart all but bleed for her. He wants to trust her so that she'll trust him to save her.]