I had the same problem when I did my bridle but in the end I did eye splices in both ends then wrapped the eye splice around the fitting once which took up the length that "creeped." For those who haven't done an eye splice in plain spectra or dyneema 12 strand it is VERY easy after a little practice. The size you can use for a bridle can be so small that it is really cheap to buy extra to practice. Getting the length right can be a little tricky but you will get it