WHEN C. C. married C. M. in Massachusetts in 2005, they expected the marriage to be forever. The lesbian couple, who lived together on the Upper East Side, had been in a relationship for five years.

“We had an incredible relationship,” recalled C. M., 39. “We had a very strong foundation.”

A year after their marriage, C. M. gave birth to a daughter, now 2 years old, and her partner adopted the baby. They asked that their names not be published to protect their daughter’s privacy.

But tensions set in, straining the marriage. There were health and financial issues, and the “stress of a same sex marriage.”

Misery replaced wedded bliss, and in December 2007, C. C., now 34, moved out.

At first it wasn’t clear how hard breaking up would be. They sought legal advice for how to handle custody, child support and maintenance. New York does not allow same-sex couples to marry within its jurisdiction, but its governor has issued an order requiring state agencies to recognize such marriages legally performed elsewhere. (Also, on May 12, the State Assembly passed a bill to legalize it and the bill now awaits its fate in the State Senate.)

But last October, in New York State Supreme Court in Manhattan, Justice Rosalyn H. Richter granted C. C. and C. M. a divorce (using their initials in the documents), making it the first such dissolution of a same-sex marriage in New York of a couple who had married in the United States. The decision recognized that the marriage was valid in Massachusetts, where it was contracted.

The divorce came on the heels of a decision in February 2008, by Acting Supreme Court Justice Laura E. Drager in Manhattan, allowing the divorce proceedings in another same-sex case to move forward, requiring the recognition of a same-sex marriage that had taken place in Canada. There has since been a trickle of gay divorces in New York.

So with the attention long focused on the rights of gays and lesbians to marry their partners, the couples often don’t consider the dark side: What happens if it doesn’t work out? said David L. Mejias, a matrimonial lawyer in Glen Cove, N.Y.

In New York, a six-month residency is required for a divorce, if the marriage was performed legally elsewhere.

Susan Sommer, the director of constitutional litigation at Lambda Legal, a gay rights organization, said that while divorce is “a painful and sometimes bitter process, having access to the structure of laws determines how you pull apart one of the most financially intertwined relationships and also gives you a neutral arbiter, a judge, to help navigate.”

C. M. said it was “devastating that we couldn’t marry in New York but could divorce here.”

“Why shouldn’t we be as miserable or as happy as the rest of the world?” she asked.

Nancy Chemtob, the lawyer who represented her, said “it was really like doing a heterosexual divorce.” Among the issues were life insurance, child support, alimony and visitation rights, and agreeing on schools.

Other states that don’t allow gay marriage have been struggling with whether to grant divorces for marriages performed in states that do. In February, a judge in New Jersey ruled that gay marriages performed outside the state are recognized in New Jersey in the case of divorce. But courts in Rhode Island and judges in Oklahoma and Texas have refused to grant divorces. And last month, the California Supreme Court upheld the state’s ban on gay marriage, but the ruling said the 18,000 existing marriages of same-sex couples can stand.

Shannon Minter, legal director of the National Center for Lesbian Rights, said those couples continue to be “entitled to be treated as married in every respect, including being able to go to court and dissolve their marriage.”

Meanwhile more states are legalizing or considering legalizing same-sex marriage. It became legal in Iowa in April, and Vermont will be the latest of the New England states to permit it when its law goes into effect Sept. 1.

David Greenan, a psychologist, family therapist and an assistant professor at Teachers College at Columbia, said that a more formal divorce process can be psychologically beneficial for a couple who choose not to continue their relationship and “helps to create a ritual of separation, a ritual for disengagement.”

That same-sex couples can’t marry but can divorce is “an incredibly negative destabilizing message,” Dr. Greenan said, that “somehow you don’t have equal rights.” He added, “Inadvertently the message is ‘We’ll help you to separate; we just won’t help you to get together.’ ”

Before Tom Hroncich of Islip, N.Y., could marry a second time in January, he had to get a divorce from a previous longtime partner, whom he declined to identify to spare him further grief. The couple had legally married when same-sex rights were extended in Canada in 2004.

Their enthusiasm over the fact that they could marry was not matched by what was happening in their private lives. “It wasn’t so blissful,” he said. He thought the sanctity of an official marriage would “help the relationship.” When it didn’t, they separated.

Not long after, Mr. Hroncich, a lawyer and the publisher of Outlook-Long Island, a monthly gay magazine, met John Malanga. Soon after, they moved in together.

When Mr. Malanga asked Mr. Hroncich to be in a committed relationship, there was a hitch. Mr. Hroncich was still married.

That marriage was dissolved on Dec. 3 in the New York courts.

He and Mr. Malanga were then married legally in Mystic, Conn., on Jan. 3. Mr. Hroncich, 41, who took his partner’s surname, is now known as Tom Malanga.

Tom Malanga said the ability to get a divorce “was an enormous help” in sealing his relationship with his new spouse.

C. C., who has custody of her daughter one night a week and every other weekend, said she didn’t consider marriage with the thought that “one day I will get divorced.”

“It is just like every other relationship,” she said. “We are not in fairytale land. It’s real. Sometimes it doesn’t work out.