In Harry Potter and the Half-Blood Prince, Harry is snooping around, trying to catch Malfoy. Once, he runs into Tonks on the seventh floor corridor, who says that she wants to visit Dumbledore.
Later at the end of the book, in the hospital wing:
And the meaning of Tonks’s Patronus and her mouse-colored hair, and the reason she had come running to find Dumbledore when she had heard a rumor someone had been attacked by Greyback, all suddenly became clear to Harry; it had not been Sirius that Tonks had fallen in love with after all.
Apparently Harry understands that Tonks had fallen in love with Lupin & why Tonks came to visit Dumbledore.
But I don't. What has Dumbledore got to do with Tonks & Lupin's relationship?
Why did Tonks visit Dumbledore?