Prince and Princess Bagration-Mukhransky, 1911

These first three images I believe to be their engagement photographs; they were engaged in the spring of that year.

Princess Tatiana Constantinovna of Russia (23 January 1890, St. Petersburg – 28 August 1979, Jerusalem), the third of eight surviving children and the elder daughter of Grand Duke Konstantin Konstantinovich and his wife, Grand Duchess Elisaveta Mavrikievna, née Princess Elisabeth of Saxe-Altenburg. Early in 1911, at the age of twenty-one, she was rumored to be considering marriage with Prince Alexander of Serbia, later Alexander I of Yugoslavia. But it appears that the year before she had met and fallen in love with Prince Konstantin Alexandrovich Bagration-Mukhransky (2 March 1889, Tbilisi – 19 May 1915, Jarosław), a Georgian by birth who was serving in a Russian Imperial Guards regiment. Her parents disapproved because of his unequal status and they were kept apart for some months, the Prince even returning to Georgia. But on his return the two became engaged. Before the union was approved, though, there was much discussion among the senior members of the Romanov family as to whether her proposed marriage with a non-dynastic prince would be deemed acceptable under the "Fundamental Laws" of the imperial family; though the Mukhranskys were a branch of a long deposed royal dynasty that had once ruled on both sides of the Caucasus, the union was not considered "equal". After much deliberation, Nicholas II legalized authorized marriages of members of the imperial family - below grand ducal rank - to persons who lacked "corresponding rank". The marriage thus approved - though it would still be considered legally morganatic - the wedding, with the Tsar in attendance, was celebrated in September of that same year. 

These five images are also said to be from 1911; the following
four look to have been taken on their honeymoon.

The couple had two children, a son and a daughter, born in 1912 and 1914, respectively. The year of their daughter's birth also saw the commencement of the First World War; the Prince would fight with the elite Chevalier Guard Regiment. In 1915 he was awarded for his heroic actions in the course of combat and reconnaissance missions. And later that year - only four years after his marriage - he was killed in combat and was posthumously awarded the Russian Empire's highest military decoration, the Order of St. George. One of the Princess' brothers was also killed in action soon after the beginning of the war, her father died only a month after her husband, and three more of her brothers were murdered by the Bolsheviks in 1918. She and her children escaped Russia in 1919, settling first in Romania and then Switzerland. Accompanying them was Alexander Vasilievich Korochenzov, an aide-de-camp and close friend to her uncle Grand Duke Dmitri Konstantinovich (who was also murdered by the Bolshviks that same year.) Having known each other for more than twenty years, the two married in November of 1921. Then, not quite three months later, he died of complications caused by the diphtheria. The Princess went on to raise her children alone and in 1946, after they were grown and both had married, she took the veil. In 1951 she became Abbess of the Mount of Olives Convent in Jerusalem where, as Mother Tamara, she later died at the age of eighty-nine.

Their children, Prince Teymuraz and Princess Natalia, circa 1915.

Princess Tatiana with her sister, Princess Vera Konstantinovna, and Princess Tatiana's children,
Princess Natalia Bagration-Mukhranskaya and Prince Teymuraz Bagration-Mukhransky.
The photograph was taken at the funeral of Alexander I of Yugoslavia, Belgrade, October 1934.

Mother Tamara, ND.