By the time King's Landing fell, Eddard knew he'd fathered a child (and possibly knew he'd fathered his heir) on his wedding night. The idea that Eddard Stark would set aside his wife, his heir, and his word to Hoster Tully in exchange for tying Casterly Rock more tightly to his Iron Throne is laughable.
- This is assuming, of course, that Tywin would let her LIVE long enough for Ned to see her again.
- Indeed. In fact, that's what happens in The Joinery.