She keeps her voice low, because as much as she wants to talk about this she's also not in the habit of broadcasting her personal life to anyone sitting around them. This is definitely for Lydia's ears only.

"No, we - we both agreed that we're not back together," she replies, shaking her head firmly. Regardless, there will still always be feelings on both sides, and she knows they don't care about each other any less. "But I think it was something we both needed, and besides - it's complicated."

Definitely increasingly complicated once she and Isaac hashed out their own feelings - or the establishment thereof.