Looking for a quote which is like "it's not for their sins, it's ours"

"It's not you, it's me."

From Wikipedia:

It's not you, it's me is a popular phrase used in the context of breaking up, and is intended to ease the dumpee's feeling in the knowledge that it wasn't their fault, but rather the fault of the dumper.

However, it's become something of a cliche, which is often taken to mean the opposite of it's original intended purpose.

The quoted article continues:

Merriam-Webster described it as a "much-reviled, often-used excuse." The Huffington Post described it as "overworked and cliched." Psychology Today argues that "opening with 'It's not you, it's me' is just going put your partner on the defensive from the start.