He's stopped telling her that he loves her, tired of being told she doesn't. It hurts just as bad as it used to. He's simply stopped saying it.
Instead he hides behind a joke about the dangerousness of picket fences. It's a good one. She buys it.
He claims he isn't being noble, but that's exactly what it is. Keeping his love to himself so she doesn't have to deal with it.
He says his eyes are clear. She buys it. His facade stays in place just as long as it has to.