Ironic statement meaning the exact opposite.
My ex partner who has schizophrenia used to say "I'm perfectly fine" when he was infact not.
I have BPD and now use "perfectly fine" If asked if ok by my best friend and I am actually not "perfectly fine"
Someone who promised not to leave but then leaves anyway. And soon enough, he's got his arm 'round a brand new girl, and while you're picking upyour heart he's been pickin' up her.