|Prince Peter with King Hussein of Jordan|
|Prince Peter with Prince Rainier III of Monaco|
In September 1939, he married Irina Aleksandrovna Ovtchinnikova, a Russian divorcee. The marriage was considered a mesalliance, and Peter lost his dynastic rights. Although he kept in touch with his mother, Marie, and his sister, Princess Eugenie, his father, Prince George disowned him.
Peter and Irina were remarried in a Greek Orthodox ceremony in 1941. He introduced Irina as a Princess, but his first cousin, King George II of the Hellenes, made it clear that the marriage was not dynastic, and Irina was not entitled to be styled as a Princess.
King George II's brother, Paul, succeeded him as king in April 1947. Prince Peter hoped that Paul would look kindly on his marriage, and restore his dynastic rights. Paul would not budge.
Peter also had issues with Paul's son, King Constantine II, and he chafed at the loss of his succession rights. He also refused to accept a change to the Constitution, allowing for female succession. He did not accept that Constantine II's younger sister, Princess Irene, was the heiress presumptive until the birth of Constantine's first child, Alexia, in 1965. Princess Alexia was the heiress presumptive until the birth of Crown Prince Pavlos in May 1967.