Close Friends
Context is important to understand a statement. The first one is about the kuffaar who supported each other against Islam. They were told that they will be enemies to each other when they faces the consequences of their unjust opposition to Islam. They will blame each other. In the second instance, it is about the ones who loves a righteous person for his righteousness. He will be with him in Jannah despite having different ranks in Jannah.
Both Surah Zukhruf and Noah’s son example are talking about after Allah’s judgment has been passed. Which we have explained before, there is no judgment of Allah today because there is no more Rasool coming . So we wait for Day of Judgment to see which relationship Allah will allow and which He won’t. It’s not a rule for today.