I am inclined to accept that Olga did not sleep with Colonel Kulikovsky until they were married. If that is the case, there is no hypocrisy about her disapproval of Mikhail's mistress.
Naturally, it is impossible to know for certain, but the evidence for me is that they married on 16 November 1916, and Tikhon was born on 12 August 1917. On this basis we have a highly fertile couple in the days before contraception was all that reliable, so if they had been sleeping together before that then pregnancy was highly likely.
In any case, from the time the two met, Olga tried to persuade her brother and Peter of Oldenburg to allow her a divorce so that she and Colonel Kulikovsky could marry. Further, he was an eminently respectable single man, whereas Natalie Wulfert had a distinct past.
Ann