When I first started smoking cigars I cut the end off too far a few times. Which is to say, past the cap. With nothing to hold the wrapper in place, it unrolled.

If your cigars are unrolling from the end you smoke, you may be cutting too deep.

I have a couple Xikar cutters and with those, I open them, lay them on a flat surface and stand the cigar up in them to cut them. I find this cuts to the perfect depth and never cuts past the cap and they don't unroll anymore.