You may have her back but only under one condition.
Orpheus looks back too soon.
Oh no! Not again!
Orpheus and Eurydice then get married. However right after, Eurydice is stung by a viper and dies.
Orpheus plays his lyre to Hades to sway him towards letting him bring back Eurydice. Hades agrees but says the he must not look at her until they are in the upperworld.
While making their way up from the underworld, Orpheus gets impatient and really wants to take a quick glance just to make sure she's there. But when he finally reaches the upperworld, he turns around to look and her but she's still making her way up through the caverns and gets swept away.