Kurt Baumeister/Relationships

Wendelin von Benno Baumeister
In the anime it's pretty much implied that Kurt supposedly never harbored any kind of love or affection for his youngest brother even when Wendelin was still a child. The first time this is shown is when Artur and Kurt were in the study and Kurt mock and insulted Wendelin behind his back when he assumed that Wendelin falsely believed that he was a Magician saying "He probably took a look at his pitiful existence he cried so much he couldn't put it back" (in reality Wendelin did have an affinity for magic but chose to keep it secret to prevent succession issues). When he suspected that Wendelin was a Magician he started to keep a closer eye on him and followed him around for a time due to the fact that he would lose his succession rights if Wendelin was a Magician. When Wendelin declared that he wanted to be an Adventurer, Kurt was actually pleased not because Wendelin found a path for himself but because it meant another obstacle would be out of his way.

Amalie Mainbach
In her own words she doesn't believe he ever loved her as he took a mistress as soon as she had his sons. She realized she couldn't count on him and they only thing she cared about was making sure her sons had a good future.

Amalie had apparently been aware that her husband was corrupt, especially after when Wendelin had returned to birthplace which caused Kurt's jealousy to be much more visible.

Kurt himself considers his family to be disposable, even proclaiming to Wendelin that Kurt can always "make a new family" even if Amalie and her children will die because of his own actions.

Ultimately, when Kurt met his demise by his own precipitous actions, Amalie was not mournful afterwards, but rather she cared more about her own children.

Rest of the Baumeister Brothers
None of his brothers cared for him as he saw all of them as a threat to his inheritance till they left the territory.