Maybe Ron is jealous of Harry and wants to have something that belongs to him for a change. The cloak gives Harry a certain freedom and mystery, and Ron might be longing for that kind of experience.
Harry might be really angry with Ron and it could damage their friendship. They've been through a lot together, and stealing something as important as the cloak is a big betrayal.
Yes, there are some out there. Some fanfictions explore this alternative relationship dynamic in interesting ways. They might rewrite the story's events and character interactions to make it seem more plausible for Harry to be with Hermione instead of Ron.
The plot could start with Harry realizing he has deeper feelings for Hermione than just friendship. He might start spending more time with her, which causes tension between him and Ron. Eventually, he could confess his feelings to Hermione, and she might be conflicted because of her relationship with Ron.
Another possible antagonist could be a dark wizard who has a special interest in the wands that Harry is stealing. This dark wizard might want these wands for his own evil plans and sees Harry as a competitor. So, he would try to stop Harry from stealing the wands while also trying to get his hands on them himself.
Another possibility is that in the fanfic's unique plot, there could be some sort of magical influence or dark magic at play. Perhaps a spell was cast on Ron that made him act out of character and punch Harry. It could also be part of a complex plot where Ron is being controlled by an outside force to create drama between him and Harry in the context of the Drarry relationship.
It could also lead to a divide within their group of friends. Hermione, for instance, might be caught in the middle, not knowing who to side with. This could create a lot of tension and conflict among the characters, adding more drama to the fanfic. If the punch was public, it could also damage Ron's reputation among their peers, as punching a friend is not an acceptable behavior in most cases.
The cloak could change his life by making him more confident. If he's able to use it to his advantage, like sneaking into places he normally couldn't, he might gain a sense of power. For example, he could overhear important conversations that give him an edge in his studies or in dealing with bullies at Hogwarts.
It could be a misunderstanding. For example, Ron might think Harry did something really bad to Hermione or their other friends. Without proper communication, his anger could lead him to punch Harry. Also, if there was some sort of magical influence or dark magic at play that affected Ron's judgment, that could be a reason too.
Maybe Harry steals wands to gain more power in the wizarding world. He could be on a secret mission to collect powerful wands that are hidden away. By stealing these wands, he might be trying to tip the balance of power in his favor against some dark forces.