"It's not about whether they beat literally or not, you old romantic," he points out, amused - and that right there is of course the difference between them.
Except that he did follow his heart when they first got here, agreeing to a blue band arrangement with Ianto, and then again when all the stuff with Spike happened. Perhaps...
"Should I try to be more romantic?" he wonders for a moment, and then shakes his head, scoffing. "No, that's your department. I'm not trying to be like you!"