Marek Vandaar was a wealthy businessman who married Alleya Mandata. The two of them had one son, Jacen Vandaar and were happy together. Then, Jedi Knight Alisia Varute discovered the Force potential of their son and asked to train him. Alleya refused because of her own experiences with the Jedi.
This caused a rift between the Marek and his wife since he wanted his son to go on to bigger and better things. The rift was settled when Alleya murdered her husband in a desperate attempt to prevent her son from becoming a Jedi.