PROVINCETOWN — The call came last Wednesday night, just over halfway into Police Officer Emmett Catanese’s 3 to 11 p.m. shift. On the line was Christian Peters, 50. He was at home in the East End and said Joe Amato, 45, his partner, had just stabbed him.

Catanese, Officer Joseph D’Andrea, and Officer Aaron Kacergis arrived on the scene to find Peters standing over the kitchen sink, bleeding profusely from the neck and his right arm, wrote Catanese in his report. In the bedroom, Catanese found a broken bottle on a set of bloodied sheets.

The severity of Peters’s injuries made it difficult for him to speak, the officer wrote. But he managed to communicate this much before rescue personnel loaded him into an ambulance: he’d just been “lying there” when Amato attacked him.

To Catanese, the specifics of this incident were new. The general situation, though, wasn’t. “I am familiar,” he wrote, “with both Peters and Amato through numerous previous calls of domestic violence at this residence.”

For more than a decade, Amato and Peters (né Costa) have shared an East End third-floor walk-up. For more than a decade, that apartment has seen a relentless cycle of violence and forgiveness.

The Provincetown police have responded nine times to reports of domestic abuse between Amato and Peters since July 2010. Peters has faced charges of disorderly conduct, destruction of property, and four instances of assault and battery. Amato has been charged with assault with intent to murder or maim, assault with a dangerous weapon, resisting arrest, and seven instances of domestic assault and battery.

Both men have reported their partners to the police. Both have required hospitalization for their injuries. Both have told authorities that violence is a constant element of their relationship.

But neither man, at any point, has been found guilty of a crime.

“When it comes to issues like this,” said Ann Burke, an advocate in the violence recovery program at Fenway Health, a Boston-based LGBT health care, research, and advocacy organization, “the criminal justice system often doesn’t operate the way that we think it should.”

No two cases involving Amato and Peters have been exactly the same. But every case file — save the most recent one on Sept. 30 — includes the same scribbled line: “Dismissed upon the exercise of marital privilege.”

Marital privilege is one of a handful of exemptions — like doctor-patient confidentiality and priest-penitent privilege — in the rules of evidentiary admissibility in trials. When invoked, marital privilege protects any and all communication between legally married persons; no one can be forced to testify against a spouse.

The inherent intimacy of domestic violence means that successful prosecution often hinges on victim cooperation in the courtroom, said Hema Sarang-Sieminski, policy director at Jane Doe Inc., the Mass. Coalition Against Sexual Assault and Domestic Violence.

Prosecutors can go forward without the victim’s cooperation, but that requires using other evidence to build the case. Whether that happens can depend on “what the D.A.’s stand is on domestic violence,” said Burke. “How willing are they to do the work to press forward on a case that’s just become a lot more difficult?” she asked.

Ten years of violence between Amato and Peters means there may be a sizable collection of witness reports, medical records, and photographs that could bolster a case.

But “decades of scholarship,” said Sarang-Sieminski, “show that for a survivor who’s had their agency taken away from them, pressing ahead with prosecution they don’t want to go forward with can be really harmful, deterring future outreach to programs and law enforcement.”

Physical abuse is rarely an isolated incident, said Burke, which is why so many victims of intimate partner violence shy away from testifying against their abusers. Typically, it comes on the heels of a campaign of intimidation, isolation, and emotional and psychological abuse.

Because of those behaviors, by the time an incident of physical violence occurs, its target usually feels entirely dependent on his or her abuser. To cooperate with prosecutors would mean losing what feels like the victim’s only support system.

And, said Burke, mainstream perceptions of domestic violence as affecting only women as victims places men who are victims of intimate partner abuse at a serious disadvantage.

“It can be very difficult for men to see themselves as victims,” Burke said. “And while, in theory, it’s not so much harder for men to get help than for women, there are fewer agencies and people out there geared at helping men.”

All of which helps to explain why the Massachusetts court system and Provincetown’s police seem powerless in changing a dangerous pattern — and why Amato is unlikely to face trial on charges of domestic assault and battery and assault with a dangerous weapon.

Two other charges, though, represent a new development in his and Peters’s history. Searching the East End apartment that Wednesday night, Officer Catanese discovered a sizable collection of Class E steroids and prescription anti-estrogen drugs. Though some of the substances bore prescriptions in Amato’s name, Catanese found no needles or syringes on the scene — indicating, he wrote in his report, that the drugs were not intended for Amato’s personal use.

Amato thus also faces one charge of possession of Class E drugs, and one of intent to distribute them. Even if invoked, marital privilege can have no bearing on that portion of the case.

Amato is currently being held without bail in pre-trial detention. He was arraigned Oct. 1 and will next appear in Orleans District Court this Thursday, Oct. 8, for a dangerousness hearing.

Peters, who was airlifted from Hyannis to Boston on Sept. 30, was discharged from Mass. General Hospital on Oct. 5.

Where to Get Help

Call Independence House’s 24-hour hotline at 800-439-6507 for an immediate response to any physical or emotional crisis arising from abuse or sexual assault, or stop at offices in Provincetown or Orleans; 857-313-6681 connects you to Fenway Health’s Cape Cod Office; 877-785-2020 provides local resource information, including shelter availability. In an emergency, call 911.