Times like this, Jack half-wishes he smoked too. He wouldn't mind a stiff drink around now, certainly!
He sits quiet for a moment, listening to Spike, watching his body language, trying to get the measure of him. And pondering. What are they trying to achieve here?
"I guess..." he says eventually, lifting his eyes to Spike's, "what's important is Ianto. He's who we're doing this for, isn't he? Ultimately, it's not even about the sex. It's about making sure we can get along, so that he can be happy."