I've had this happen to my favorite pairs too, and it's definitely frustrating when jeans that fit perfectly start falling apart in that specific spot. The friction thing is real, but I'd push back a little on just accepting it as inevitable. The tightness of skinny jeans definitely accelerates wear there, but how much depends on a bunch of factors - your body shape, how often you wear them, even the fabric blend matters. Some pairs hold up way better than others.
For repair, it honestly depends on the hole size. If we're talking small tears or thinning fabric that hasn't fully blown out yet, you can hand-stitch an iron-on patch on the inside - it'll buy you more time without looking obvious from the outside. There are fabric patches made specifically for this that work pretty well. But if the hole's already substantial and the fabric around it is shredding, a professional tailor might be your best bet if you really love these jeans. They can reinforce the area or do an invisible mend depending on how much damage there is.
That said, after wearing the same pair since 2015, they've honestly done their job. If repair costs more than it's worth to you, it might just be time to retire them. But if you want to keep wearing them, catching it early and patching makes a real difference - way easier than waiting until the hole gets bigger.