During and by the end of the Seven Years War, Britain faced several challenges both at home and abroad. The American colonies' war was costing Britain enormous sums of money. Initially, the British probably thought the American colonists would support the British against the French, as in the mind of the British, the colonists were loyal British citizens. While some Americans fought side by side with the British military, most Americans remained on the sidelines, preferring not to take an active role. This left the British to fill the ranks of their military force from Britain, with little or no assistance from the local colonists.
It is important to remember the battlefront was on two continents, America and Europe. The British were forced to maintain an active military in a combat role on the American and European continents. The added expense was in addition to the ongoing financial costs of maintaining colonies in other parts of the world. The financial drain on the Empire led to several consequential decisions that placed the British in a challenging political position with the Americans and with the British loyalists living in the colonies.
The main issue was how to recoup the conflict's cost, leading the British to impose heavy fees, tariffs, and taxes on the colonists. As one might imagine, this was met with stiff resistance from the Americans, who believed the war to be a conflict between two European powers (France and Britain).
The Americans had significant financial relations with both and had no desire to alienate either side economically. Not to mention the fact the British imposed the fees without consultation from their American partners, leading many to begin to think that the best interest of America was to be a sovereign nation. Even British loyalists saw the imposition of fees and restrictions on the colonists as problematic and potentially jeopardizing years of relatively profitable relationships with their American counterparts. Revolution would shortly follow the ill-advised financial policies of the British government.
Another issue is that the war placed a wedge between the Native American tribes occupying much of the territory the war was fought on and the British. Though never having as good of a relationship with Native Americans as the French, the British nonetheless needed to maintain at least some level of cordiality to protect their own and the American colonists' interests as they expanded westward into the Ohio Valley and the Great Lakes regions. From the start of the war, Native American tribes mostly tried to remain neutral to the extent they could. Unfortunately, the British military's aggressive actions in dealing with the native tribes forced many of the tribes to choose sides. The British were never able to recover and reestablish friendly relationships with Native Americans after the war officially ended.
The issues brought on by the Seven Years War led to the American Revolution and the decline of the British Empire as a world power.