Despite the age difference, it was obviously a marriage without insurmountable conflicts, perhaps because Eric mostly stayed on his Erichsburg and Calenberg Castle, while Elisabeth resided at her wittum Münden.

For example, in 1528, Elisabeth accused Anna von Rumschottel, a member of the landed gentry and for many years her husband's mistress, of being responsible for complications during her second pregnancy.

Elisabeth managed to force Eric into giving her a more profitable wittum than their marriage contract required: instead of the district of Calenberg in the Unterwald region, which contained Calenberg Castle, Neustadt and Hanover and provided little revenue, she received Oberwald, with the towns of Münden, Northeim and Göttingen, which provided more revenue and greater political weight.

On October 6, she informed Landgrave Philip I of Hesse of her conversion and with his assistance, invited the reformer Anton Corvinus to move from nearby Witzenhausen to Münden.

When Eric I died on 30 July 1540, he helped her become co-regent of Brunswick-Calenberg-Göttingen, together with Philip I of Hesse, despite fierce resistance from Duke Henry II of Brunswick-Wolfenbüttel.

The physician Burckard Mithoff, the court judge Justin Gobler and Heinrich Campe MJ completed the team with which the princess wanted to implement her reforms.

At the urging of her son, Elisabeth cancelled the agreement with the court of Hesse and Eric married the ten years older Sidonie on 17 May 1545.

In 1546, one year after the accession of her son Eric II, Elisabeth married Count Poppo XII of Henneberg (1513–1574), a younger brother of the husband of her eldest daughter.

She had to watch with horror when her son Eric II in 1557 married her youngest daughter, the Lutheran Catherine, to the Catholic High Burgrave William of Rosenberg, to provide for her economically.

When Elisabeth completed the difficult journey to Münden to attend the wedding, she found that Eric had deliberately given her the wrong date and that the marriage had taken place some time earlier.

Her children commissioned an epitaph with her portrait by the sculptor Sigmund Linger from Innsbruck, which was erected in 1566 in the St. Giles Chapel of the St. John's Church in Schleusingen.