Sherlock Holmes Question?

Question

In the "Final Problem" where the reader is first introduced to Prof. Moriarty, when Holmes askes Watson to flee to the continent with him Watson agrees, stating that his wife is away for some weeks visiting relations.
Then in the second story of the book "The Return of Sherlock Holmes" in the "Adventure of the Norwood Builder" we find that Watson has sold his medical practice and is again living with Holmes in Baker Street. What happened to Watson's wife, and his marriage? And in which story are we, the reader told about it?

Answer 1

In the first story of The Return of Sherlock Holmes, "The Adventure of the Empty House", Watson refers to his "recent bereavement" which is assumed to be the death of his wife.