The young Elector was forced to marry by his mother, ostensibly to produce legitimate heirs to the Electorate but truly to end the liaison between John George and his mistress, Magdalene Sibylle "Billa" of Neidschutz. Another consideration was an alliance between Brandenburg and Saxony.Immediately after assuming the Electorate, John George lived openly with Billa, and she became the first ever Official Mistress (Favoritin) of an Elector of Saxony. Eleonore was relegated to the Hofe (the official residence of the Elector) while John George moved into another palace with Billa.
Desperate to marry his mistress, John George tried to murder Eleonore, but was prevented by his younger brother, Frederik August. When John George tried to stab Eleonore with a sword, the unarmed Frederick turned the impact away with his hand, leaving him with a lifelong handicap.