long term LS couples who eventually divorced anyway — was the LS related or not, im trying to understand

this is morbid sorry. but im asking bc im in my head about it. f48 m50, 21 yrs married, 13 yrs in the LS. we are FINE. like genuinely fine. but i was at a thing last weekend (regular birthday party, not LS) and ran into a couple we used to play with in like 2017-2019, very long term LS, like 18+ yrs in. except they showed up separately. her with a new bf, him solo. they divorced last yr. nobody in our circle knew. i went home and couldn't stop thinking about it bc i remember them being SO solid. they hosted in their basement, beautiful house, kids grown, looked like they had it all. and now they don't. i texted another couple from that era and apparently this was the THIRD long term LS couple from our extended circle that's divorced in the last 3 yrs. all 3 were 15+ yrs married, all 3 were 8+ yrs in the LS, all 3 looked rock solid from the outside. and i can't stop wondering. was the LS related. like did it accelerate something, or expose something, or distract them from something. or is it just statistics — 50% of marriages end and LS marriages aren't magically exempt. so im asking ppl who were in long term LS marriages that ended. or ppl who watched close friends in long term LS marriages end. was the LS related to the ending. did it come up in the divorce reasons. did one of you fall for someone, was it actually a money/work/midlife crisis thing that had nothing to do with LS, was it that the LS was a band-aid on a marriage that was already done. im not trying to be a vulture im just trying to understand the pattern bc all three of these couples scared me a little and i can't articulate why