Answer:
The main factor that contributed to heat the relations between Great Britain and the settlers of the Thirteen Colonies was the huge tax burden that Britain placed on America.
At the end of the French and Indian War, Britain decided that it was the American settlers who had to pay for the cost of the war. Therefore, it began to tax hard on trade, imports, publications, and everything related to the colonies.
In turn, the economically pressured colonies began to demand from Britain both tax cuts and representation in Parliament, under the slogan "no taxation without representation". This led to a state of permanent conflict between both sides, with tragic and tense events such as the Boston Massacre and the Boston Tea Party, which led to a state of total conflict that unleashed the American Revolutionary War.