Saved By The enemy

Its been 7 years since the second wizarding war had ended.
Everyone has been settled down in their life. Everything in the wizarding world seems to be quite peaceful. No missing reports, no death-eaters sightings and no other mysterious activities. But the war heroine, the Gryffindor princess, the brains of the golden trio had gone somewhere five years ago. No one knows about her. Likewise the malfoys had been long forgotten from the wizarding world from the day Draco malfoy sacrificed himself to save the war heroine exactly 5 years ago.
What happened that made Hermione the brightest witch of our generation to disappeared from the wizarding world? Why did Draco malfoy save Hermione, his arch-nemesis, the mudblood and the part of golden trio whom he had loathed for years? Does Draco malfoy really dead? Does he really hate Hermione or is that all just a mask to hide his true feelings?