Actually I'm glad that the question about "divorce" rates was asked as it seems that there is (at least in the UK) a significant legal difference between Civil Partnerships and heterosexual marriage.

The grounds for dissolution of a civil partnership are that the partnership has broken down for good (i.e. irretreivable breakdown) by -
Unreasonable behaviour or
Two years seperation, and the consent of the other partner or
Five years seperation or
Desertion

Unlike heterosexual marriage this does NOT include adultery as a ground for dissolution of the partnership.

Like many on this thread I had understood that there was little real "discrimination" between the two forms of partnership in the UK now I'm not so sure........