Ah so the Doctor's back to using a screwdriver? A shame, I think I'm the only one who likes the sunglasses.
The Doctor and River most likely have some sort of polyamorous relationship. I'm absolutely convinced that the eleventh Doctor and Clara were time travelers with benefits by "Day of the Doctor" at the latest, and River's made it clear at times that she fancies men besides the Doctor. They're adults, they can work out their boundaries and guidelines.
Or, maybe the other husband in the story turns out to be the eleventh Doctor and Christmas is a previously unannounced multi-Doctor story.
What 11 was boning Clara?
Yuck
How is that "yuck"? Sure, there's an age gap of a couple hundred years, but they're both consenting adults, what they do together is their business.
Honestly, I never got the impression they were actually sleeping together, but the Eleventh Doctor and Clara were definitely "more than friends."