This behavior occurs in all poultry. It's called being "broody" which basically means the hen is sitting on the nest, and barely gets up to eat or drink. Broodiness signals that the hen wants to hatch eggs and raise chicks. Since your dove has no partner, and her eggs are infertile, then she cannot produce squabs, but believes she can. It's normal pigeon behavior to sit on the eggs. I'd advise getting her a cock, because the reproduce once a year and have two broods, so the hen will continue this behavior. Now that you want it to stop, remove the eggs, and try to compel the hen out of the nest as often as possible.