Why would a robin build and nest and not return to it?

A robin may build a nest and not return to it for several reasons, including disturbances from predators, environmental changes, or human interference that could make the location unsafe. Additionally, if the female robin feels that the nest is in a poor location or if she is unable to lay eggs due to health issues or stress, she might abandon it. In some cases, she may simply choose to build a new nest in a more suitable area.