For all his complaining about her, in "Spark of Insanity" when Jeff asks Walter if he loves his wife, Walter says "of course" with no hesitation.
Dunham was adopted, which wasn't a big deal to him. He mentions he doesn't have an interest in finding his birth parents. The moment of heartwarming is in his autobiography when he has his first child and as he holds his infant daughter he realizes this is the first blood relative he's ever met.
The entire Achmed Junior sketch from Controlled Chaos shows Achmed and AJ bickering, but at the end, when Jeff asks AJ what he'll do if Achmed can't accept his not wanting to be a terrorist, we get this beautiful exchange.