It took Harry a full week to recover from the "Delusions of Romantic Grandeur," and the exact cause and nature of the phenomenon were never explained to his full satisfaction. Even towards the end of his recovery, Harry still suspected that Malfoy himself had "cast some spell to make me think that way - probably because he secretly wishes I were in love him with!" Luckily, Ron and Hermione had been around to point out to Harry that he was still under the influence.
As for Hedwig, Harry had to sit her down and lecture her on the evils of passing notes out to the wrong people. "Professor Snape thinks I'm in love with him now!!" Not to mention that Ginny Weasley and Neville Longbottom had been avoiding him as well. Hedwig's only explanation of her behavior was the usual affectionate nip on Harry's ear; he replied by sending her all the way to Egypt with a four-word note addressed to Ron's brother Bill.
"Bill,
Hello!
Sincerely,
Harry"
Of course Hermione had protested, arguing that the owl simply knew better than to deliver any such incriminating letters to Malfoy. Although, even she couldn't defend the Snape episode.
Slowly relationships began to heal - necessarily in the case of Neville, since Harry and he depended on each other's help to pass potions. Snape continued his usual biting remarks in class, but made no further mention of the note or flowers, and Harry was forced to conclude that it had all been a joke. Ron forgave Harry his "illness" but became immediately wary anytime Harry mentioned anything about Malfoys, inner thoughts, or interior design. Harry did not often mention interior design.
Draco Malfoy did not take any special pains to avoid Harry, but whenever their eyes met, he did seem a bit nervous. Harry assumed it was because Malfoy feared another blundering attack - at least, that is what he told Hermione and Ron. But there was still some nagging part of him that believed Malfoy was actually worried that prolonged exposure to Harry would result in his losing his cool and giving in to those long-suppressed desires.
"And when that day comes, I'll know just what to do."