The report went on to say Foster dragged her by her hair, physically threw her out of the house and punched her in the head eight to 10 times.
He faces allegations that he inflicted great bodily injury, forcefully attempted to prevent a victim from reporting a crime and possession of an assault weapon.
Foster was a first-round draft pick last April out of Alabama, and although injuries hindered the start of his rookie season, he did win NFL Defensive Rookie of the Month in December and finished as the team's second-leading tackler.
"Rueben Foster will not participate in team activities as he is tending to his legal matters", it read.
The 28-year-old is also charged with misdemeanor possession of a large caliber weapon.
Foster appeared in Santa Clara County Superior Court for arraignment Thursday afternoon. If convicted of all charges, Foster could go to prison for almost a decade.
It was a mutual decision by the Niners and Foster that he remain away from the team for the start of the offseason program, according to NFL Network's Jim Trotter.
Foster last Thursday was charged with three felonies, two of which are related to domestic violence, and a misdemeanor for possession of ammunition for an assault rifle. "Our office handles between four and five thousand domestic violence cases each year".
In an official statement, the district attorney's office said Foster's live-in girlfriend was bruised and suffered a ruptured eardrum.
The 49ers released a statement attributed to chief executive officer Jed York, general manager John Lynch and coach Kyle Shanahan on Sunday night saying that Foster will not be participating in team activities as he goes through the legal process stemming from his February 11 arrest.
National Football League offseason programs are voluntary and divided into three phases, starting with a two-week session limited to strength and conditioning. "Reuben is aware that his place in our organization is under great scrutiny and will depend on what is learned through the legal process". In a statement, the 49ers organizations said: "We will continue to follow this serious matter".
The NFL team announced on Sunday night that the former Alabama All-American would not take part in the offseason program - at least not until Foster's legal troubles are resolved. The judge also issued a no-contact order between him and the victim.