Originally Posted by DarthGore:
“how about if she's the Doctor's mother???
look at this way - she knows the Doctor's real name, she kinda looks like a younger version of the woman from Tennant's final episode who people believe to be the Doctor's mother, and presumably if that person was a Time Lord, then they'd have the same amount of lives/reincarnations, and time isn't linear, so why couldn't it be the Doctor's mother, live out an ENTIRE timeline as River, and then still get back to the Time War to die with the rest of the Time Lords.
they did drop the hint that whatever River's secret is, it's not as simple as being his wife, so why can't it be his mother? who else could he trust almost implicitly apart from his own family?”
Interesting theories, but...
the Doctor has stated that he'd know if there were any Time Lords left - the only reason he didn't feel the Master was because the Master used a chameleon arch.
It's implied the Doctor will tell River his name, rather than have been given it by her "there's only one person I would tell my name to, only one time I could". (Which sounds sort of Weddingy) (or deathy!)
Time Lords are forbidden to meet each other out oof sequence - it's one of the Laws of Time. Clearly the Doctor and River do exactly that. Repeatedly.
I thought the comment about not being as simple as being a wife was more a reference to the non-linear and unorthodox nature of their relationship. And the fact they are different species.