Yes. Ella was a very creative and moody person at times. It was an invasion of her privacy to see her imperfections.
Not sure if Ella knew how children were created. Louis XC1 and Marie Antoinette spent years before getting it right...
Serge wanted children, and by having them over fulfilled his emotional needs for being a parent. He did not care if that would hurt Ella or not, especially since Serge was fond of Alexandra of Greece too.
Ella did not sign on to be a parent to those two, and they were forced upon her without her agreement (Serge was the master remember ?). It is natural for her to resent the intrusion of children into her life. It happens with relatives staying too long in other cases.
Surely, it did not take 7 years for the courtiers of Louis XCI (?) to explain to his Majesty the facts of life.
The progressive Princess Alice was known a proponent of sex education. If Victoria of Battenburg were sex educated, it's unlikely that her sister Ella would not be.
Supposedly, Ella was fond of Alexandra of Greece too, although it's not known what she felt about Serge's extraodinary attachment to his sister-in-law.
To be fair, when Paul broke his word to the Emperor & abandoned his children (knowing the inevitable consequences) where else could Marie & Dimitri go but to the uncle & aunt who had been nearest to Paul & who were closest to them?
According to Marie Pavlovna, the Grand Duke Serge followed Paul to Europe when he eloped with his mistress & made a good faith effort to persude his beloved brother not to abandon his children.
Marie Pavlovna, 1902:
"Uncle Serge & Aunt Ella came to see us for a few days before departing for abroad. They too seemed sad, cast down, there was that in their attitude towards us, my aunt's in particular--which aroused in us a vague presentment."
"Our aunt & uncle's trip abroad, it now appeared, had been to Rome to meet our banished father; they would soon come back, & we would see them, we were told....We found both of them overcome with sorrow; they cried over us a long time. My uncle sharply denounced Mmm. Pistolkors; he accused her of having divorced a suitable husband to ruin my father's life & future, and of now taking him from his children, who needed him."
"..despite the great sorrow that my uncle felt at his brother's mesalliance he could not conceal the joy he felt at the fact that from now on he would be able to keep us entirely to himself. He kept saying "It's I who am now your father, & you are MY children."
The Grand Duchess Ella did not blame Serge, but instead harbored an implaccable resentment toward the Grand Duke Paul. Ella wanted no contact with Paul & his wife, whatsoever.
1908
" My aunt's attitude toward my father throughout all these happenings (Marie's engagement) hurt him profoundly, he held it against her always...My father told me later that my aunt had exasperated him beyond measure--that she was distant & so different from her former self, he could not make her out."
1918
"My aunt had never become reconciled to the thought that the wife of my father--fully pardoned & re-established in his rights by the Emperor--had received an official, although morganic, title and was recognized by everybody, beginning with court. The hostile feeling that she bore for Princess Paley; she transferred to my father's children by his second marriage."
Clearly, the Grand Duchess Ella was in no position to stipulate to the Emperor (or to the Grand Duke Serge) that she would not tolerate her abandoned neice & nephew becoming members of her household because she resented sharing her husband's affections.