It's because Neville is his friend (and probably his best friend that isn't Merlin, but then Merlin's family and that's different?) that Asato doesn't clam right up and refuse to answer.

He does blush deeply and fold his ears down as he looks away. "It's..." He's really embarrassed.

"I ... don't have a mate," he manages, reaching up to hugs his own shoulders and clearly feeling uncomfortable on top of sick and in pain now.