Something from the blog I found on the web about he possible marriage between Ekaterina and Nicholas and is told by her friend Count Sheremetev...he says:
"And suddenly, all hopes were dashed. Sheremetev remembers as a close friend: "I come once to the house of Ekaterina Petrovna and heard:"It's over! "- she says ... That's what it turned out: talks about her marriage with cesarevitch lasted long; Maria had a sympathy for this union, but with a precondition, that Ekaterina Petrovna should have her preliminary education. Had in mind primarily the transition to Orthodoxy. Her mother immediately replied and categorically refused. But it was only a pretext, the real reason for the refusal was in the complex relationships between Maria Alexandrovna and Teresa, both disliked each other, felt that their role was played by "old Nassau-Darmstadt account ", to the fact that staid and restrained Empress was irritated by the ecstatic behavior of the Oldenburgs."
Obviously those two women never liked each other because of this,so,does anyone know what was "old Nassau-Darmstadt account "?