The phrase "cruel twist" refers to a situation where something unexpected and unfortunate happens in a way that feels unkind or unfair. Full definition
Maybe it is for the best that my row mate left before she could witness the ultimately happy yet cruel twist at the end. (rogerebert.com)
But unlike the Dude who abides, or Larry Gopnik, who endures one cruel twist of fate after another or perhaps Barton Fink, who's in over his head, Llewyn is fighting against his own talent. (indiewire.com)
In a particularly cruel twist, the body regards excess fat consumption as stressful and releases even more FKBP51, which exacerbates the problem. (newatlas.com)