This is the area where a lot of force is applied when the legs open. It is also the area where the inner thighs always rub against each other when walking.
I make a point of sewing two thick thread stitches (seams that are sewn together) on this area.
The first stitch is made with #6 thread.
Then sew them together with an even thicker thread, #0 thread.
Then lockstitch (sewing by girdling the edge of the fabric)
Then turn the garment over and chain stitch it.
Chain stitches tend to fray easily, but we use chain stitches because of how the bite will look. Even if this stitch breaks, there is no structural strength problem because of the two ground stitches above.
Last bartack stitch
I spare no effort to make the best jeans I can.