I think John's lying to Aeryn. He doesn't trust her any more then with his heart than he did before, because she hasn't done anything to prove that he can. But he's going to let himself have the illusion of it, the physical connection and affection, because it's easier than fighting, and it gives Aeryn a reason to stop digging. She thinks he's opened to her, but we don't see him actually do so. Not until spoiler.