The United Kingdom of the Netherlands was created by fusing the southern Netherlands with its northern neighbour, and was made as a buffer-state between the powers of Prussia and France. However, the Dutch weren't able to keep their southern people, the Belgians happy. For example, southern bishops had forbidden working for the new government, which made the south under represented. This and the dominance of the north over the south reminded them of their history of being suppressed led to the Belgians revolting against the Dutch and declaring themselves an independent state; the Kingdom of Belgium.
The state of Belgium was recognized by the five major European countries during the Congress of London in 1830, but the Dutch weren't done yet. William I returned to the fight for Belgium with the Ten Day's Campaign, this plan was largely successful but the interference of French troops made William finally recognize the new state with the Treaty of London.
But what if the north handled the south better? What if the Dutch were able to secure most of what is now Belgium? That is what this timeline is about.
In this timeline the Dutch tried to ease tensions between the Catholic south and Protestant north. After long discussions with southern catholic leaders, they accepted their new country, and more Belgians began to be represented in the government. As more Belgians accept this government, William could easily silence the ones who still wanted an independent south. By giving some land in Wallonia to France, they dealt with the Walloons who thought they were being suppressed by the Dutch majority. And because of the actions he took, the Belgian didn't scream Wij willen Willem weg, but they happily said Wij willen Willem.