Historically speaking, the marriage of King Henry VIII of England and Anne Boleyn is significant for two main reasons.
First, this marriage led to the splitting of England from the Catholic Church. Before this, Henry VIII had been a staunch Catholic. However, his first wife, Catherine of Aragon, did not bear him a male heir. It was important for any king to have a male heir to ensure the succession. Henry wanted a male heir and felt he needed to end his marriage to Catherine so that he could marry someone who would, he thought, bear him a son. The pope, for various reasons, refused to annul the marriage. This led Henry to break with Rome and set up the Church of England, which would grant him an annulment.
Second, this marriage led to the birth of a girl who would one day become Elizabeth I of England. Elizabeth was one of the most important English monarchs in history. Her long and successful reign was seen as something of a golden age for England.
For these two reasons, this marriage was historically significant.