LOS ANGELES—The estranged wife of the man who allegedly went on a shooting rampage in a Southern California office building earlier this week that left four people dead — including a 9-year-old boy — said Saturday that she couldn’t fathom why her husband targeted people who had treated her like family for more than a decade. Police say the suspect, Aminadab Gaxiola Gonzalez, had targeted the mobile home brokerage company, Unified Homes, and had personal and business relationships with the victims. His wife, Aleyda Mendoza, had worked in the Orange County business for more than 10 years as a broker assistant. Mendoza, in a text message to The Associated Press, said she and Gaxiola have been separated for two years and “he never told me anything about where he was staying or what he was doing.” “I can’t understand what went through his head to make such a terrifying decision,” …