exult at

exult at (something)

To feel great happiness due to someone or something in particular. I doubt you could say anything to upset them right now—they're still exulting at their engagement.
See also: exult

exult at something

 and exult over something
to rejoice because of something; to rejoice about something. We exulted at the end of the hostilities. The citizens exulted over the downfall of the dictator.
See also: exult