On October 5 1812, Ludwig van Beethoven arrives in Linz, Bohemia to confront his younger brother. Beethoven has heard that his brother Nikolaus Johann van Beethoven intends to marry his housekeeper, Therese Obermayer. Beethoven left Teplitz, where he had been staying for health reasons, to stop the wedding.
Johann is a successful apothecary in Linz. He is not troubled by the money problems that afflicted his more famous older brother. Beethoven stays over a month at Johann's house but is not able to persuade him not to marry Therese. Beethoven's objects to Therese because he does not think she is a suitable wife. She is a housekeeper! More distressing, she has given birth to a daughter out of wedlock some four years earlier, when she had been a housekeeper at another house. She had been 19 years old at the time. Her daughter's name is Amalia.
The brothers will quarrel over the next month but Johann refuses to listen to his older brother. Beethoven even approaches the bishop of Linz to complain that his brother is living in a common law relationship with his housekeeper. The bishop sensibly suggests that, if that was the case, it would be a good thing that they marry. Next, Beethoven will go the police to try and stop the marriage by having Therese arrested. He does not succeed. His brother marries Therese on November 8, 1812. Beethoven is not present. There is no record of him having sent a wedding gift.
There are mitigating facts that do not excuse, but at least provide some context for Beethoven's actions. Beethoven had from a very young age been responsible for his two brothers. When he was 18 years old he had been forced to go to court obtained an order that half of his father's pay be given to support the family. His father had been a notorious drunk. Beethoven is also experiencing a highly emotional and stressful part of his life. His hearing is deteriorating. He has lost the love of his Immortal Beloved. His brother's proposed marriage, when he himself had not been able to marry, must have been truly upsetting.