A) Instead of providing a list of reasons that you want him to fail, why don't you...

B) Instead of providing a list of reasons for which you want him to fail, why don't you...

A) sounds wrong to me; however, if I can say 'the reasons I want him to fail are XYZ', why can't I say A)?

B) sounds correct; however, 'the reasons for which I want him to fail' sounds clunky.

Am I misunderstand something slightly?