Ten only stares back at River as she stares at him; she hasn't met this face in the Library and buries further any guilt or sorry's. She's standing right there and he can't even tell her.

What should he do? Should he pretend not to know her? No, that would only backfire. However, there isn't really any polite way to tell River this is there?

A swallow and dry remark, "Don't call me sweetie, River. You might upset the Ms." A short pause, "I'm sorry. I'm so, so, sorry. But I don't know how we happened. We can definitely get to know each other and be friends. But this face of me can't be your husband in Nautilus."