*sigh* Well, actually he also kept information about what the Jedi Council was trying to do from Anakin, at least in the RotS novelization, but it never sat well with him regardless of which person he was withholding information from. I don't know if Luke was necessarily ready so much as "needed" the truth in RotJ. Vader had already done the damage by burdening him with the information. Obi just confirmed it.

In any case, secret love affair is not what One Path is about. That is not the kind of secret he'd keep from anyone, especially Anakin, whom he loved and trusted as a son/brother. The fic also deals quite a bit with Anakin, his good and bad points, psychological problems, the way that Palpatine manipulated and used him, and the friendship he had with Obi so anyway yeah, I know what you're saying.