Maybe they split because of all the comments that Jake has receive lately about him being "so sexy" and stuff like that, maybe he wanted to be single again
... Kirsten, dont cry, i can stand you and i love you
...
Ok, now in a serious way... i always thought that was a weird couple, i mean, Kirsten and Tobey broke up and she started to date Jake... come on!! Tobey and Jake are a little bit look a like!!... that was the first sign they wouldnt be together for a long time!!.