I got a feedback request from her boss, so I listed 3 things she could do better. Pretty sure her boss wouldn’t follow up.
Had my 1-on-1 with her and she asked “Any feedback?”. I thought for a second, then just went “what the hell, let’s do it”, and spent the next 10 minutes telling her all the things she does wrong.
She was incredibly thankful for the feedback as no one else was willing to give her direct feedback.
She didn’t change overnight, but we had an absolutely great relationship after that. If I didn’t like something she did, I told her right away.
I even blew up at her about a year later because she kept cutting me off on a big presentation. She apologized and it never happened again.
It was a gamble, but it paid off.