According to her Wikipedia article, Frederike Sophie was married three times. Her first marriage was to Prince Frederick Louis Karl of Prussia in 1793. The marriage did not succeed, but he died of diphtheria in 1796. However, she bore three children by him, including Princess Frederica Wilhelmina Luise Amalie of Prussia. She hoped to marry Prince Adolphus, Duke of Cambridge, but Frederike's aunt, Queen Charlotte, had George III call off the engagement. She quickly married Prince Frederick William of Solms-Braunfels after she became pregnant by him in 1798. She bore seven children, four of whom survived to adulthood. Then he became alcoholic, dying in 1814 while divorce arrangements were being made. She met Prince Ernest Augustus, Duke of Cumberland in 1813 and, despite Queen Charlotte's objections and non-attendance at the wedding, married him in 1815. She bore two stillborn children and a son, George.
Hanover required male succession so the sovereigns of Hanover and the UK diverged when William IV died and Victoria became Queen of England. Ernst Augustus then became King of Hanover and Frederike became Queen of Hanover. Her son George succeeded Ernst Augustus as King George V of Hanover. Georg V married Marie of Saxe-Altenburg.