Though badly educated, he was full of good intentions and a hard worker. His marriage to Luise von Mecklenburg-Guestrow was not an arranged marriage as he had chosen her himself after their meeting during his travels abroad. 
However, his first mistress, Elisabeth Helene Vieregg (1679-1704), was the daughter of the Prussian Ambassador. In 1703 he contracted a bigamous marriage with her; but after the birth of a son, she died on 27 June 1704. Elisabeth Helene's position was now taken by the 14-year-old Charlotte Helene von Schindel (ca1690-1752). She gave birth to a short-lived daughter but found herself replaced by Anna Sophia Reventlow (1693-1743) who had met the king at a masked ball. 
Anna Sophie Reventlow first became mistress to the king, but in 1712 he married her bigamously "with the left hand". However, once his Queen was dead, he then married her and made her Queen of Denmark. This was the cause of bitter arguments in the Danish royal family, even when she became the mother of three children. 
The first twenty years of his reign saw Denmark involved in the Northern War, which ended with the peace of Frederiksborg on 3 July 1720. He continued the absolutism policy, established 240 new schools, and sent missionaries to Lapland, Greenland and the Danish East Indies. In 1728 a large part of Copenhagen was destroyed by fire. 
After his death on 12 October 1730, Queen Anna Sophie begged for mercy from her stepson, the new King. Although she was deprived of most of her inheritance, she retired to her estate at Klausholm where she lived in comfort till she died in 1743
 

Source: Leo van de Pas.