"You don't want to do something right now?" she teases.
No, the groceries will spoil, and you can't afford to buy them again.
"OK," says Kara, smiling, "thanks for getting those groceries for us. Later then." She leaves you, picking up her lingerie on the way out.
You put the groceries away and fix Kara a pasta dinner while you think about what just happened.
Now you don't think you can honestly get any relief with Kara, as it would be not just a physical betrayal of Erica now but also an emotional one.