Pull the carpet/rug out from under somebody's feet - Idioms by The Free Dictionary
pull the carpet/rug out from under somebody's feet
pull the carpet (out) from under (someone's) feet
To suddenly or unexpectedly remove or rescind support, help, or assistance from someone; to abruptly leave someone in a problematic or difficult situation. I felt like someone had pulled the carpet out from under my feet when my health insurance said it was going to stop paying for my medical bills. I'd love to up and quit my job, but I just can't pull the carpet from under their feet like that.
pull the ˌcarpet/ˌrug out from under somebody’s ˈfeet (informal) take the help, support or confidence away from somebody suddenly: I was just about to ask her out when she pulled the rug out from under my feet by telling me she’s getting married next month. ♢ The bank’s pulled the carpet out from under his feet, unfortunately. It looks as if he’ll have to sell the business.