Joan Redfern
From Tardis Wiki, the free Doctor Who reference
Nurse Joan Redfern, widow of Oliver Redfern, was a nurse at Farringham School for Boys, where John Smith was working.
After John Smith became the Doctor again, he requested she join him as a companion, but she dismissed the idea immediately by asking the Doctor, "If you hadn't decided to come here on a whim, would any of these people have died?"
In an alternate future viewed by both she and John Smith, she became his wife, widow, and the mother of their two children.