They say the peel n stick borders are great because you can easily remove it to reposition but I think it removes too easy. The border is peeling up in places and actually coming off at one end. Did I do something wrong?

No, but you probably have a humidity problem in the area you installed the border in. Would suggest you get some wallpaper/border paste and use that to repair the areas that have come loose from the wall.

Well, for one thing, what is the room and size of the room where the border is located? Depending on where it's located and the size and humidity conditions of the room, using a peel and stick border might not be the best choice to use for the selected area. I agree that using a paste of some kind might be the solution. Might want to even try some other, stronger adhesives. However, depending on the conditions, no matter what you use, you might continue to have problems with using a border or even big pieces of wallpaper.

Thanks!