It is not entirely clear whether he was Anna's lover, but it is certain that his mistress was a sister of Ernst Johann Biron, the future duke.
[citation needed] The most powerful man in the duchy, Bestuzhev was implicated in intrigues to sell the crown to various German princes, whereupon he was forbidden to interfere into internal affairs of Courland.
After Duchess Anna (who had supported him heretofore) accused him of mismanaging her affairs and embezzling the ducal treasury, only the intercession of his sons - Mikhail Bestuzhev-Ryumin and Aleksey Bestuzhev - helped him avoid criminal prosecution.
He publicly denounced the appointment as a semi-exile and on this account was commanded by his rival, Biron, to settle into retirement.
In addition to his two sons, both counts, he had a daughter, Agrafena Petrovna, who was married to Prince Nikita Fedorovich Volonsky.