Knowing
Cathy didn't like cheesy things. She absolutely couldn't stand mushy movies, or romance novels, and would always voice her hate for them when the occasion called for it.
This was why she could never express how truly satisfied she was when she was having sex with Jamie. While the sex part was all well and good, it was knowing it was with him that really made it special. Knowing he was sharing something so intimate, knowing it was him joined with her, knowing that they were one - that was what made her smile and blush.
Of course, she'd never say all that out loud. It would give her husband a big head, and he'd tease her about it.