Definition & Meaning of "nightmare dressed like a daydream"in English

What is the origin of the idiom "nightmare dressed like a daydream and when to use it?

The phrase "nightmare dressed like a daydream" originated from the lyrics of the song "Blank Space" by Taylor Swift, released in 2014. The line is used metaphorically to suggest a deceptive or illusory appearance that initially seems pleasant or enticing, much like a daydream, but later reveals itself to be a distressing or nightmarish experience. In other words, it is mainly used to convey the idea of a situation or person that initially appears attractive or desirable but ultimately proves to be problematic, challenging, or unsettling.