"He'll be working the room and most-likely dancing with every available lady he can." Justin wouldn't put it past his father - especially knowing this is a limited-time engagement and he'll be ...well, gone. Again.
While standing there, he could practically see the wheels turning in Demelza's head and at one point thought that he had done just what he hadn't intended on doing - which was providing pressure. He swallowed hard but kept the nerves from appearing on his face when he thought for sure she would turn him down. It wouldn't be the end of the world, but he was glad when she'd agreed that the evening of dancing sounded fun.
"Good. Just think of it as an extended birthday celebration. All of your friends will be there and we can dance as much as we'd like - just showing up at the same time and having a....well, appropriately, having a ball."