I think this is the story you're looking for.
By: midori Haru
Meeting, attraction, courting, commitment. For most of the world relationships form in the normal fashion from start to culmination. Naturally normal isn't enough for Sesshoumaru. And he wonders why he runs into problems trying to build a relationship from the wrong end.
Rated: M, Drama/Romance, Chapters: 61, Kagome H., Sesshomaru, Complete
This is on ff.net. I don't know if it's on this site.
EDIT BY WICCAN: This story would definitely be rated MA on our site, NO YIMs!!