Why did brian o connor and Dominic dorreto split up at the end of Furious 7?

At the end of "Furious 7," Brian O'Conner and Dominic Toretto part ways primarily due to Brian's desire to prioritize his family and leave behind the dangerous life of street racing and crime. Brian decides to retire after realizing that starting a family with Mia is more important than continuing with their high-risk lifestyle. Their split is also a poignant moment, symbolizing Brian's growth and the respect between the two friends as they acknowledge the need for different paths in life.