Sam's promise to Leah? In Eclipse, Twlight Saga?

I can't quote but he generally had promised to be with her forever and all that stuff that comes with being in a serious relationship. I think they had planned a future, in more detail, with each other before he imprinted on Emily. So when he feels like he broke all the promises it's a reference to having to abandon their planned future together because he imprinted on Emily. That's what I got.