Ron had watched Hermione drift away, knowing that they both needed to speak with other people and mingle. It was the last thing on his mind, but he decided he'd try to find his family and at least thank them for coming.
With a glass of champagne in his hand, and tugging at his collar briefly, Ron went through the crowd, chatting briefly with a few friends as he looked about, trying to hunt down a red-headed Weasley. He knew which one he should find first.
He spied his sister, sitting on her own for a moment at a table and picked her as his destination. But even from a distance, he noted her lack of champagne, and he paused and sort of shoved his glass onto a neighboring table, making some brief apologies, abandoning it there before he approached her.
"Ginny," he said as he came up to the table, and put a hand on a chair, "Let me sit with you?"