Mask.
She blamed the sunglasses. They were his mask. They were his way to hide what he wanted and yet show the world what he could be. Sometimes it scared her to think that he would always hide him self. They say masks hide things, but he always said that masks could enhance a person. Horatio was fine, he didn't need enhancing, and he was interesting without his eyes being covered. He then told her it was sunny in Florida and she knew he was just beating around the bush. And then at night he would take his mask off for her. And her fears went away, until he went back out the next morning.
