Why must an ether be present when a Grignard reagent forms?

An ether must be present during the formation of a Grignard reagent because it plays a critical role in stabilizing the reagent and maintaining it in solution.1

Specifically, the oxygen atom in an ether possesses nonbonding electron pairs. During the reaction, the ether shares these lone pairs of electrons with the magnesium atom of the forming reagent. This process of complexation stabilizes the highly reactive Grignard reagent, which is essential for its successful preparation and subsequent use in synthetic organic chemistry. Common solvents used for this purpose include diethyl ether and tetrahydrofuran.12