Most of what we know about Ella isn't from surviving writings, I don't think. Nicholas and Alexandra wrote many letters to each other, and these survive, along with both their diaries, which are particularly useful about their courtship. Nicholas and Alexandra left many records of what type of marriage they had, that it was a love match. Yet, the marriage of Nicholas and Alexandra, in terms of politics or royal marriage of serving the country, was something of a disaster. In contrast, Ella and Sergei's marriage is barely documented at all, and there are certainly no diaries, nor I believe letters. In light of this, guesses about the perhaps unhappy nature of their marriage have abounded. But, it seems to me their marriage worked well politically, and as a royal marriage especially in terms of Moscow. This a interesting contrast to the marriage of Nicholas and Alexandra, and it must be said that Sergei and Ella's marriage was happy, in its own way.