A Eurowings Airbus A320-200, registration D-ABNL performing flight EW-6812 from Palma Mallorca,SP (Spain) to Dortmund (Germany) with 117 passengers, was enroute at FL380 about 80nm south of Luxembourg (Luxembourg) when the crew descended the aircraft to FL320. About 7 minutes later, about 30nm south of Luxembourg, the aircraft initiated a rapid descent to FL100 and diverted to Luxembourg for a safe landing on runway 24 about 16 minutes after leaving FL320. The airline reported a technical defect in the cabin pressurization system prompted the diversion to Luxembourg's Findel Airport.