Estrangement was separation from one's family due to conflict over differences of opinion.
Jean-Luc Picard and his father Maurice Picard were estranged as a result of their differing ideas about what Jean-Luc should do with his life; while Jean-Luc wanted to join Starfleet, Maurice preferred that his son remain at home and tend the vineyards of Château Picard instead. Sadly, Maurice died before they could make up, something Jean-Luc always regretted.
In 2370, when attempting to develop a relationship with Jason Vigo, whom he believed to be his son, Jean-Luc told Jason about his estrangement from Maurice and expressed his desire that history not repeat itself. (TNG: "Bloodlines")
Raffi Musiker became estranged from her son Gabriel Hwang over her neglect of her family. Contributing factors included her devotion to the Romulan refugee resettlement program, her snakeleaf habit, and her beliefs in what her son called "conspiracy theories" about the synth attack on Mars. (PIC: "Stardust City Rag")