His other friends like Shikamaru would use his intelligence to come up with a plan. He would likely analyze the situation carefully, find out who the main instigators are, and then come up with a strategy to either make them change their minds or expose their true motives so that Naruto can be freed from this forced marriage.
Sasuke would probably be very against it. He has a strong sense of justice and would see this as completely wrong. He might directly confront those who are forcing Naruto into this situation.
Kakashi would probably be a bit concerned. He cares about Naruto like a student and a son. He might talk to Naruto privately and tell him to give it a chance. At the same time, he could also have a word with Hinata's family if he feels the forcing is too much. As for Sakura, she might be a bit jealous at first, but then she would realize that Hinata is a good person and try to encourage Naruto to be more open - minded towards the marriage.
Naruko's friends would have a range of reactions. Her female friends might gather around her, giving her emotional support and advice. They would tell her to be strong and not let this forced marriage break her. The male friends, like Kiba, might be more ready to take action. They could try to intimidate those who are forcing the marriage. As for Sasuke's friends, they could be divided. Some might think this is a good opportunity for Sasuke to move on from his past and settle down. Others might worry that it will make Sasuke more withdrawn, as he might not be ready for such a commitment. They would all be watching the situation closely, ready to step in if things go wrong for either Naruko or Sasuke.
Hinata would be heartbroken. She loves Naruto deeply. Her world would shatter. She might try to find out the truth behind his death, not believing that his friends could do such a thing without a good reason. And she would probably hold a grudge against those involved.
One way could be that Naruto discovers it's all a big misunderstanding. Maybe someone is manipulating the situation for their own gain, and once he uncovers the truth, he can put a stop to the forced marriage.
If Naruto has leukemia in a fanfiction, his friends' reactions would be complex. For example, Kiba might be angry at the situation, feeling that it's unfair to Naruto. He would try to find ways to make Naruto feel better, like taking him on walks with Akamaru. Rock Lee would be inspired by Naruto's fight against the disease, seeing it as another form of training. Tenten would help by getting any items or herbs that might be useful for Naruto's treatment. And all of them together would form a strong support network for Naruto, constantly reminding him that he's not alone in this fight.
One possible reason could be that Naruto is afraid of endangering his friends. He has many powerful enemies, and he might think that by staying away from his friends, they won't be targeted. For example, Orochimaru was always after Sasuke, and Naruto might fear that his closeness to Sasuke could put Sasuke in more danger.
One possible consequence is that he could lose the trust of his friends. If everyone believes he is responsible for something his sister did, his friends might start to distance themselves from him.
It could be a character from another important ninja clan, like Hinata perhaps. Since Hinata has always had feelings for Naruto and her clan is also a significant part of the village, Minato might see it as a good match.
His father might be extremely disappointed. As a former Hokage, he would have expected Naruto to uphold the family's honor. His mother would probably be heartbroken, having always believed in Naruto's good nature.
One possible reason could be to protect her. Naruto might believe that by leaving, he can draw danger away from his sister. For example, if there are powerful enemies targeting him, he doesn't want his sister to get caught in the crossfire.