Please help me find this story! Here is what I know...
Story was completed.
Set in modern times.
It starts with Kagome/Inuyasha, with them being friends with Sango/Miroku.
It talks about Kagome's back story and how they met Kikyo and how Kagome invited her into their group.
It covers how they would talk about a movie they had seen, but Kagome was not invited.
Kagome says if it happens again they are done.
Kagome runs to the restroom before they are to go to a party, only to go back downstairs to find they had forgotten her again.
Sesshomaru and his friends are there and see this happen and invite her along with them.
Kagome comfronts her old friends and basically tells them they are done.
She starts hanging out with Sesshomaru and his friends and later starts dating him.

I believe you are talking about "Progression" by Sidhe

www.dokuga.com/fanfiction/story/3344/1?author=137

Its rated Ma so no Yims.

I think you might be looking for "A Christmas to remember" by LibraCourt.

www.dokuga.com/fanfiction/story/9591/1

rated MA so no Yims

That was it mystical lady! Thank you! Farein, thanks for the new story! I have yet to find that one! Thank you both for the help!