It wasn't a matter of trust. Joseph trusted Claudia more than he trusted anyone else. He hadn't told her because telling her would make it too real and, at the time, he hadn't known if what they were doing was real to Hannah. Why get his hopes up?
His brow furrowed when she questioned him about Sam. Sam was... different. Sure, he cared about her... and he'd been quite happy with her. She was special to him, there was no doubt about that but... Hannah.
"It's... similar," he finally answered. "I mean... Sam is special to me but, I don't know, Claudia. I've wanted Hannah for... for as long as I can remember but, yeah, I care for Sam a lot." He paused uncomfortably. "Why?