As someone who has also had these issues with the crotch of pants wearing out, I would also suggest trying these options. It's a combination of stretching and

As someone who has also had these issues with the crotch of pants wearing out, I would also suggest trying these options. It's a combination of stretching and friction. Jeans have it especially bad because they have prominent seams right where the thighs touch, causing an extra large amount of friction. A gusseted crotch (which I believe the Ballroom jeans have) both helps with the stretching and moves the seams around.