In 1936, the King of England, Edward VIII, abandoned his throne so that he could marry the woman that he loved. It turns out that there was at least one other regal person in the 1930s who renounced his right to a throne for marriage.
The February 3 1931 Toronto Globe contained this article about Prince Lennart of Sweden, who married against his grandfather the king’s wishes:
Wikipedia mentions that Prince Lennart (1909-2004) actually became Lennart Bernadotte. His marriage to Ms. Nissvandt produced four children, before they divorced in December 1971. Four months later, Mr. Bernadotte married Sonja Haunz, and they had, in turn, five children of their own. He became part of the Luxembourg nobility in 1951, becoming the Count of Wisborg.