Its a sure sign that you need to quit wearing pants. I guarantee it will solve your problems.
Fuck, it was a joke, sorry.
Is there a certain point that they tear at? could try reinforcing that stitch with some dental floss. (for example, the crotch rips, because there is a 2 way seam, just re-sew the seams for a few cm with dental floss, on top of the original.)
I dunno honestly, never had this problem.
Maybe you need to lose weight?