It could be the Ministry of Magic. If the Ministry decides that Harry's relationship is a threat to the stability of the wizarding world, they might take measures to separate them. His love could be brainwashed or sent away to a far - off place, leaving Harry heartbroken.
It could be Voldemort. Voldemort might use Harry's love as a weapon against him. He could either kill her or turn her against Harry. Another possibility is Draco Malfoy. Maybe Draco tricks Harry's love into thinking he's a better choice. Or it could be a new, unknown dark wizard who targets Harry through his love.
Well, one possible plot could be that Harry's love is taken away due to some dark magic. Maybe an enemy casts a spell that makes his love forget about him. Another could be that Harry has to sacrifice his love for the greater good, like to save the wizarding world. And also, it might be that there's a misunderstanding between them that causes the loss of love.
His friends, Hermione and Ron, would surely help. Hermione with her intelligence and Ron with his loyalty.
It could be a new dark wizard who has a vendetta against Harry. This wizard might have created a spell specifically designed to target Harry's emotions, as he knows that Harry's strength often comes from his love and friendship. By taking away his emotions, he hopes to weaken Harry and make him easier to defeat.
Voldemort could be the main antagonist. He might have seen the potential in Harry's twin and decided to get rid of the twin to weaken Harry or use the twin for his own dark purposes.
In 'Harry Loses His Emotions Fanfiction', it could be that Harry experiences a really traumatic event. Maybe he witnesses the death of a very close friend in a battle. This shock is so great that it makes him shut down his emotions as a self - defense mechanism. He then becomes cold and distant, and the story could be about how his friends struggle to reach the old Harry again and help him heal.
Well, he might feel extremely lost and out of place. His identity has been so tied to his magic throughout the series. He could face a lot of ridicule from those who once feared or respected him for his magical abilities. Maybe he'd have to rely on his non - magical skills like his courage and loyalty more than ever.
Maybe in the fanfiction, Harry's twin could be lost in a magical accident. For example, during a wizarding battle, the chaos causes them to be separated, and Harry spends the rest of the story trying to find his twin.
One possible reason could be that he's constantly being underestimated or not given the credit he deserves. In some fanfictions, his friends might take his contributions for granted, which could lead to his temper flaring up.
Well, maybe he stumbles around blindly for a while, bumping into things and getting into all sorts of comical situations. He could also rely on his friends more to help him get around until he finds his glasses.
In this fanfiction, it could be that the pressure of being 'The Chosen One' finally gets to Harry. All the battles, the losses he has endured, and the constant threat of Voldemort might push him over the edge. He could start acting erratically, pushing away his friends and allies because he no longer trusts his own judgment.