Electron pair structure and molecular pair geometry of dim ethyl ether?
I usually call these electron geometry and molecular geometry. If that is what you are talking about, then see below.
Dimethyl ether has 3 central atoms that need to be considered for geometry. You can't make a blanket declaration about the geometry of something with more than 1 central atom.
Anyway, dimethyl ether has 2 methyl groups. In both cases, those methyl groups have Electron Geometry of Tetrahedral (4 electron groups around central atom). Since they are also connected to 4 different atoms (3H and 1 O), they also have Tetrahedral Molecular Geometry.
The Oxygen in the center (like water), has 2 separate bonding groups and 2 lone pairs. This makes for an Electron Geometry of Tetrahedral.
On that tetrahedral form, the shape the C-O-C bonds make is a bent shape, so its Molecular Geometry is Bent.