Very very explicit fic where seehomaru kidnaps kagome and keeps her in a cave, and the Inuyasha squad are looking for her. The entrance is sealed with magic and hidden, but eventually kagome breaks the seal but realizes she loves sesshomaru much more than the cheating inuyasha. One of my favorite mature fics and I'd really like to find it again, it was on ff.net when I read it originally

Could it be this one?

Just Another Lemon by Tiegrsi
This story began as a one-shot and became massive quite by accident. ::::Sesshomaru has gone into heat, and finds Kagome willing to put up with his antics. Kagome thinks he was unable to find a suitable woman, and came to her as a last resort. Perhaps there are some things Kagome needs to learn...:::: (Nominated Best Lemon 3 Times in 2007, 2008 by Dokuga, Inuyasha Fanguild, and A Single Spark; Won Second Place Best Lemon [1Q Dokuga in 2008])
Rating: MA - Universe: Canon - Status: Complete - Category: Chapter Stories - Genre: Action, Drama, Erotica, Kink, Romance - Updated: 01-21-11 - Created: 01-15-11 Chapters: 11

www.dokuga.com/fanfiction/story/5006/1

Please note: RATING IS MA! NO YIMS!

Thank you for trying, but this isn't it. It was on ff.net when I read it,if that helps