"I would order a ticket, taking refuge in the mercifully theoretical nature of airline schedules on dates at such a marvelous remove that they could never possibly come to pass."
This lady hates traveling so she forces herself by phoning the agency first.
Please explain or rephrase
It lacks context, but it seems she orders her ticket a long time before she needs it, knowing that it will never appear as the airline schedule will have changed before then. So she won't have to fly anywhere.