Without further info, and given the (now admitted) hysterical title to the thread, maybe they took-off knowing they would / might need to call in at EINN? Our SOPs allow "replan enroute" if fuel is tight, using the intended destination as the Flt Plan dest. If at the "replan" point, not enough remains, then we call up and arrange a pitstop.... i.e. we can depart with not enough fuel to make dest with usual div/reserves etc., but reassess later on.
This might be due unusual high load / strong headwinds or MEL issues...