Ross had a brother named Tanner, some sort of businessman, but he was out of town. The rest of the Carringtons were all exceptionally nice to her and she left with a glow of happiness.
It was only later, when she went over the events and conversations of the evening, that she realized the truth. It came to her in a flash, and once she'd opened up that view, she knew it was the right one. Nice as they'd been to her, Ross's parents didn't think she was right for their son. It was obvious.