I don't know if this story is old or complete for that matter, but I can assure you it has been some time since I read it.
it was a great read but I cannot remember more than one particular scene: Sesshomaru and Kagome are trying to break their mating bond (forgot whay :/ i guess it wasn't planned or so, not sure if it was "completed" anyway...) and to do this Sesshomaru knows there has to be a betrayal. Thinking back on his father, who broke the mating bond with his mother, he comes to the conclusion that infidelity is the way to go. Promising to Kagome he will sleep with another woman. He cannot do so, forcing Kagome instead to try to sleep with another man. The bond is then broken, without Kagome actually sleeping with this guy, because there was an betrayal of trust by sesshomaru. The breaking is painful and when Sesshomaru wakes up again he thinks Kagome betrayed him and.....that's it, all i remember...
Have you heard of this fic? I have been trying to find it everywhere. I would be happy to know if it still exists at all