He decided to save his wife from the underworld because he misses her. But she was not able to retyrn with orpheous.
Oprheus decided to rescue her because he loves her. Orpheus greatest weakness is love. when he went to the underworld he used his Lyre to soften hades heart and he did. hades gave orpheus a chance and said that her love would follow her until they reached the upper world and if he looked down she will be gone forever. but when orpheus reached the top in his anxiety and for waiting long he looked back. and once again she was gone but now forever.