Read up on these forums and it seems like the best way to take care of crotch tear is to get a patch. But how would a patch on the inside stop the outside from wearing away? Any other ideas on how to PREVENT crotch tear? I want to do what I can before it may or may not happen. I also read something about restitching the crotch area just so it is more durable, where would you stitch?
you are just thinking toooo much into it. just get a patch, go to the tailor, tell them you want to reinforce the crotch area from the inside (the part where the two "legs" meet, in other words, the middle, where your penis would be if it were small, not the zipper part), in the event a rip happens the patch will cover up the hole, or prevent it from being as bad as it would be without the patch.
other ways to prevent:
don't be as active with your jeans on. if you are really that worried wear them only when you know you wont submit them to much punishment.