I have my doubts about Maria's flirtation with a guard in the Ipatiev House, when you look into that in any detail its not much more than chinese whispers as there's not one 1st hand witness to that story only 2nd, 3rd and sometimes 4th hand.
Also it was at a time when the Ural Bolsheviks were trying to discredit the family/exaggerate the difficulties of keeping them held prisoner (the officer letters). As we still don't definitively know who actually made the final decision to kill all of them, servants included, the Ural Soviet or Moscow. However, Maria was known for having 'an eye for the men' and took people as she found them, so you never know but I think her open friendly nature was misconstrued or even deliberately twisted to be used against the family in that instance.