Shepard lets out sigh she didn't quite realize she'd been holding. She appreciates what he's telling her, but believing it is something else entirely. Maybe she's just stubborn that way. But it's hard not to to feel at least the tiniest bit guilty of even considering focusing her energy on this place when she knows what is still out there waiting for her at home. That doesn't mean that she won't. It's just the letting go that she's struggling with. Having Kaidan right next to her helps with that almost as much as it hinders. A constant reminder of home. But also a constant reminder of who she is.

"There is... a lot going on here that we don't know about," is her strange way of saying that she agrees with him. It seems just vague enough for someone to overhear and misinterpret her meaning: that she intends to find out exactly what all 'that' is.