Mary Elizabeth was a daughter of the Frederick III of Schleswig-Holstein-Gottorp (1597–1659) from his marriage to Duchess Marie Elisabeth of Saxony (1610–1684), a daughter of John George I, Elector of Saxony.

On the occasion of the wedding, the last sword dance in Hesse was performed at a festival in Lollar.

His father drew Louis into the government business in the year after their marriage in 1651.

Louis tied extensive political relations with Sweden via Maria Elizabeth's sister Hedvig Eleonora, Queen of Sweden.

Marie Elisabeth had eight children; she died in 1665 in child birth.