Solubility is related to intermolecular forces. In order to solubilize in water, a compound must have favorable interactions with water through intermolecular forces, in order to separate the water molecules from each other.
The carbon chains on either side of the oxygen in the ether are nonpolar and are unable to form hydrogen bonds. They can only interact with the water through London dispersion forces, which are the weakest of the intermolecular forces. The water molecules prefer to hydrogen bond with each other rather than solubilize the ether.
The oxygen of the ether can hydrogen bond with the water, but the nonpolarity of the carbon chains overwhelms this interaction.
