RXR was ready to start the demolition work on Aug. 6, but a Ralph Lauren representative contacted the developer July 28 and asked it not to move forward. The retailer instead asked RXR to issue it a credit equal to the cost of the work, which RXR estimated was about $440,000, according to the suit. Ralph Lauren never responded to RXR’s estimate or to a letter RXR sent the company Sept. 3, the suit says. Its sole reply came Oct. 19, when Ralph Lauren said it was no longer obligated to expand on the fifth floor, citing “the doctrines of ‘impossibility’ and ‘frustration of purpose,’” the suit says.