Ichigo would probably be devastated. His trust in relationships would be severely shaken. He might become more withdrawn and focus even more on his battles and training, using it as an escape from the pain of the betrayal. He could also become more cynical about love and people in general.
I think his family would be the first to help. His sisters could bring him cold compresses to reduce the fever, and his father would use his medical skills. And from the Soul Society, Renji might come to check on him, as he and Ichigo have a sort of friendly rivalry. He would want to make sure Ichigo gets better soon so they can have their next sparring match.
Ichigo would also experience a period of sadness. He values his relationships, and when one is broken through betrayal, it would hurt him deeply. He might isolate himself for a while, brooding over what happened. But ultimately, he would use this experience to become stronger. He'd learn from it and be more cautious in future relationships, while still maintaining his core values of loyalty and trust.
Another possibility is a jealous rival. Maybe there's someone who is jealous of Gohan's power or his relationship with certain characters. This rival could do things to annoy Gohan and push him to the edge of his temper.
A new player on an opposing team could be the cause. This new player might be overly cocky and disrespectful towards Kuroko during a game. They could constantly taunt him about his lack of presence, which finally gets on Kuroko's nerves and makes him mad.
It could be Vegeta. Maybe Vegeta does something really underhanded like stealing Goku's senzu beans or trying to take all the credit for a victory that Goku also contributed to. Goku, being a fair - minded person, would get angry at such behavior.
One of his friends could be the cause, accidentally. Maybe a friend makes a deal with a shady character without realizing the consequences. This deal ends up putting everyone in danger, and Yami gets mad at his friend's naivete and the mess they've created.
He might become withdrawn at first. Since he's used to being in control and having a certain dynamic in their relationship, Bella's anger could shock him into pulling back. He could go off on his own for a while to think about what he did wrong.
There could be some very strange and out - of - the - ordinary fanfictions out there that might have such a plot. However, this kind of plot goes against the normal character relationships and storylines in the original Bleach series. Usually, fanfictions tend to focus on more traditional themes like battles, friendships, and power - ups rather than such extreme and uncharacteristic situations.