^ Indeed. He's not stepping out on his wife because from his perspective she's already died. Well, she died when he first met her, but that is he'll never see her again after that last date they had where he gave her the screwdriver. So he's basically a widower - is he not allowed to move on. Assuming the wedding counted of course, which is fine by me.
He started as this old man who was sort of like a father figure to Amelia Pond, but over time, as Amy and Rory grew up and the Doctor kind of became like their son. At the end of "The Doctor, the Widow, and the Wardrobe," when he shows up at the Ponds' house for Christmas, I felt more like he was their long-lost son who ran away from home, too scared to come back for fear of what they might think of him, only to return to find that they still loved him very much and just wanted him home.
I actually really like this part of Eleven's relationship with the Ponds. It's not consistently portrayed or perfect, but it's something that's very unique and I like it.