you answered your own question. The event ended. 

lougait is correct. Unfortunately classic fusions - including epics - must be completed before the timer runs out. only fragments can be done later on.

it wasnt exactly publicly advised (how are new players supposed to know that). i have only been playing 3 months

other games give time after  events end to spend or use rewards earned

I understand your frustration, but the length of the fusion is listed in the calendar. There is also a timer for the fusion when you go to the portal for the legendary and its epics/rares.