For Tchaikovsky, his friendship with von Meck was tainted by realisation that his financial well-being depended on her. When their epistolary dialogue just started, Nadezhda heard a word from her friends about the composer's difficulties, and perhaps she paid a bit too generously for the small music works that she ordered to him. In the future, Tchaikovsky himself would ask von Meck for money on several occasions, until in 1878, she decided to provide him with the regular support of 6,000 rubles a year, by instalments or as one payment. On top of that, von Meck often invited the composer to stay at her houses and estates in Russia and abroad.
Tchaikovsky never stopped thanking his patroness and emphasised the fact the von Meck's support helped him concentrate fully on his work and quit working as a teacher at the Moscow Conservatory: 'In Moscow, when I was thinking I was done, I wrote a phrase on my draft [of Symphony No. 4] which I forgot and remembered about it just recently, when I got back to work and found it. Next to the title, I wrote: 'In case of my death, please send this notebook to N. F. von Meck.' I would like you to keep the manuscript of my latest work. Today, I am alive, safe and, thanks to you, I can dedicate myself entirely to my work, knowing I am writing something that will not be forgotten.'
Despite endless gratefulness and spiritual affinity, the composer set boundaries for their friendship with von Meck. In particular, Tchaikovsky gently rejected her suggestion to switch to a more informal style of conservation.
Several curious things happened over the years of their relationship: von Meck made his music popular outside Russia, he dedicated Symphony No. 4 (it was Nadezhda who suggested phrasing the dedicatory inscription as 'To my best friend') and Orchestra Suite No. 1 (his own intention) to her, both sought ways to become relatives and encouraged the wedding of the composer's niece Anna Davydova and von Meck's son Nikolai. However, with time, their relationship grew to be more formal.
On one hand, it was caused by Nadezhda's personal and financial problems and her deteriorating health, on the other, Tchaikovsky's social and artistic life became much more intense, which did not encourage sincere and frequent contacts. By the late 1880s, their letters became more sporadic and resembled terse reports of events.
Tchaikovsky notices the first signs of their perishing relationship at the end of 1887: 'Sometimes, I feel that we are growing apart. However, never before have I thought as much and as often about you as in the recent days. <...> Ten years ago, at this very time of the year, I was living the worst, most tragic moments of my life, and God knows what would have happened to me if you hadn't appeared with your moral and financial support. I keep every tiny detail of this memory of the past long gone in my mind. The feeling of gratefulness and awe to you penetrates every bit of my soul! I drew so much moral strength from your letters back then, from your infinite sympathy and friendship!'
In September 1890, Nadezhda abruptly broke off their correspondence and stopped supporting the composer financially. Tchaikovsky took it very hard since he had sincerely believed their friendship had been based on a spiritual connection. When von Meck blamed ending their friendship and support on her poor financial situation, Tchaikovsky believed it to be a very feeble excuse.
The offence caused by 'the best friend' stayed with Tchaikovsky to his last days. The letters that survived to our days carry signs of his love and appreciation of his distant patroness that Tchaikovsky used to express with utter sincerity: 'Often during the day, it occurs to me that no matter how many modern pessimists deny the possibility of happiness, I am a living proof against their axiom, for I am happy in my hermitage as much as a person can be happy at all. Being free and having a haven of my own—this is what I have always dreamt of, and if I have it, that means I am happy. Wishing for more would be crazy thinking and ungratefulness. <...>Thank you again for everything: every moment of my life I remember to whom, after God, I owe the happiness I described above. <...> Yours, P. Tchaikovsky.'