For as good as she is with brazen speeches, delicacy in words is not something Shepard is particularly skilled at. (Fortunately, most of their relationship exists in the comfortable silence...with occasional innuendo.)

She doesn't exactly have a word for her relationship with Garrus. Cop-out though that may be, excepting very few of her Alliance friends (Anderson and Chakwas, to be specific), she's known him longer than anyone and he has become a fixture in her life. Despite any possible circumstances, he'll always be her first officer. Because, while she likes to weigh the opinions of other people against her hard tactical data, his is the only one that carries any significant weight. Weight enough to really influence her decisions.

While she'd like to believe they have an understanding about the very real possibility of death in the near future, and are both capable of taking it like the soldiers they are, she'd be truly devastated to see him killed or gravely injured. I can't imagine she'd gotten any work done after he'd been shot in the face, not until he arrived snide and ready to work.