This may be a theory but Folklore has the fact that Kyuubi are also commonly portrayed as lovers.

These love stories usually involve a young human male and a Kyuubi who takes the form of a woman. Sometimes the Kyuubi is assigned the role of seductress, but often these stories are romantic in nature. Such a story usually involves the young man (unknowingly) marrying the fox, and emphasizes the devotion of the fox-wife. Many of these stories also possess a tragic element — they usually end with the discovery of the fox, who then must leave her husband.

So the story could be that Yondaime's wife could have been Kyuubi who took the form of a Woman. You can see where I'm going with this..

But I agree Terra It's funny