I actually had an idea somewhat similar to this one. After the war, Harry and Fleur are an item (idk how, she just didnt get together with Bill). They work as cursebreakers, and a recent expedition had them exploring a necromancer's tomb. to beat his trap…
Harry died during the Battle of Hogwarts, but his sacrifice allowed everyone else to take down Voldemort. Yet the troubles only began there. There was no prominent figure to rally around, and so what was left of the Order and the DA were unable to take on…