The United Nations is discussing the Puerto Rican status question in its decolonization committee again this week, but it is just another event that will make headlines here on this steamy island while Washington pays little attention.

Puerto Rico's 3.2 million U.S. citizens are suffering an identity crisis that is strong even by local standards, which have been honed in a 30-year love-hate affair with the mainland.

More than ever, their ambiguous commonwealth status appears outdated, useless and impossible, but local politicians are hopelessly unable to agree on the way out.

A barrage of Reagan administration decisions has shattered whatever faith anyone had here that the island mouse could cozy up to the mainland elephant without getting hurt in the process. The U.N. decolonization committee debate, led by Cuba and Puerto Rican independence advocates, will point that out.

"They didn't single us out to be hurt, but we are being hurt, and there's a great insensitivity to the fact that we're being hurt," said former governor Rafael Hernandez Colon in an interview. Hernandez Colon is the chief defender of the commonwealth faith, the idea that the custom-tailored ties that bind Puerto Rico and the 50 states can be restrung somehow to work once more.

The U.N. committee is almost certain to reject that idea, voting as it has for most of the past 10 years that Puerto Rico is truly a colony and that its future ought to be self-determined under U.N. auspices, that is, it ought to be independent.

Washington has always ignored such votes, and the General Assembly has merely taken note of the committee report.

But last year the committee for the first time voted also to have the General Assembly debate "the colonial question of Puerto Rico" this September. Such a debate, if it materializes, would bring the island to the world stage as an embarrassment to Washington.

The State Department has always insisted that the issue is a domestic one in which the United Nations has no role. U.N. Ambassador Jeane J. Kirkpatrick, speaking in San Juan for July 4th celebrations, reiterated President Reagan's endorsement of statehood for the island, but said the decolonization committee vote would have "little effect" on U.S. policy.

The feeling here now is that nothing Puerto Rico does or says has much effect on U.S. policy. Items:

The huge new tax bill now before a House-Senate conference committee would close a loophole that allows U.S. corporations to assign millions of dollars in profits to Puerto Rican subsidiaries. The island's treasury department says the action would derail its entire economic development program, to the tune of perhaps 30,000 jobs and $4 billion in investments, but frantic pleas from island officials have fallen on deaf congressional ears.

The Caribbean Basin initiative, designed to prop up staggering economies in El Salvador and elsewhere, would ruin Puerto Rico's rum and tuna industries, island officials say, by lowering tariff barriers to rum from Jamaica and tuna from Panama. "You can't help your neighbors by hurting your relatives, but that's what they're about to do," Secretary of State Carlos A. Quiros said.

Reagan made Puerto Rico a guinea pig against its will for an experiment replacing the food stamp program, which involves 57 percent of all islanders, with a cash grant program, hoping to do the same thing nationwide. Last week, one month after the complicated and expensive switch was implemented, a House committee voted to make the island switch back again. The issue is still up in the air.

Reagan administration fund cuts in the Comprehensive Employment and Training Act (CETA) program eliminated 25,000 jobs, causing the unemployment rate to go up by 2.5 percent. It is now at a record 24 percent, which means 240,000 Puerto Ricans are on the streets. Newspapers note a jump in the suicide rate; one hotel had 112 applications for one carpenter's job.

"The United States is not aware of the volcano it's sitting on here," said Cliff Depin, chief of the International Ladies Garment Workers Union local. "The workers are basically hard-working and conservative, but how long can that last? There's no jobs to go to in the states either."

Washington has expressly forbidden Puerto Ricans to travel to Cuba for the Caribbean and Central American Games, despite outrage from several thousand islanders who had paid for tickets and transportation months ago. Independence Party leader Ruben Berrios plans to go anyway and expects to be arrested. "The only reasons for commonwealth status were economic development and civil rights. Now we have no development and, if they jail me, no rights either," he said.

Reagan named a special task force on Puerto Rico early in 1981 to funnel the island's concerns to him, but refused to reveal its members until that June to keep them from being bothered by Puerto Ricans. Since then the group has been all but useless, islanders on all sides of the status question agree. "We didn't expect much," Quiros said.

These accumulated slights and outrages "make me feel as though no one up there likes me," Quiros said. Historian Oscar Morales Carrion said the island now feels "a sense of estrangement" from the mainland.

Islanders carry U.S. passports but pay no U.S. taxes and do not vote in mainland elections, and their representative in Congress cannot vote either. They fly their own flag but are defended by the U.S. military; they use U.S. dollars but live on half as much per capita income as do Mississippians, the next-poorest Americans.

Still, the roads are good and the culture is purest Yankee, for 2 million Puerto Ricans travel so regularly back and forth to the mainland that no one knows how many live here permanently.

Carrion noted that patriotic turnouts here on July 4 and at the July 25th Commonwealth Day rally were revealingly tiny. "People say the hell with it, I've lost my job, let's go to the beach."

To make things worse, the island seems evenly and firmly split on what to do next.

Hernandez Colon's Popular Democratic Party, advocating a revamped commonwealth status, controls the legislature by leaf-thin margins. But the party is splintered and he lost the 1980 governor's race by an equally tiny vote to the man who wants Puerto Rico to become the 51st state, Gov. Carlos Romero Barcelo.

The vote was 47 percent for Hernandez Colon, 47.2 percent for Romero and the rest for independence parties.

The legislative result, of course, is near-paralysis. Animosity between Romero, Hernandez Colon and Berrios, the "three kings" of island politics, is so strong that Hernandez Colon suggested a special presidential envoy like Philip C. Habib might need to be appointed to get them talking again.

Hernandez Colon called in January for a plebiscite on statehood, yes or no, and Romero promptly agreed. Both claim they would win such a vote, but clearly both are unsure and prefer to stall.

Hernandez Colon now berates Romero for failing to send a plebiscite proposal to the legislature, and Romero berates Hernandez Colon for failing to have the legislature send a proposal to the governor's office.

Berrios would boycott any plebiscite, even one offering independence as an alternative. "You can't have a referendum in a concentration camp," he said. He says his party's 6 percent of the vote would double if its real strength could show, but that islanders have been taught to fear independence as only an end to food stamps.

"You have made us drug addicts on food coupons, and statehood means more addicts," he said. "We are on the way to becoming a tropical South Bronx, with the same programs here and the same failure."

All recent U.S. presidents have said that if Puerto Rico will only decide what it wants, Congress would be happy to grant it. That is not certain. Statehood would bring in seven relatively liberal Democratic House members representing 3.2 million impoverished Hispanics in grave need of vast sums for education, housing and other federal benefits.

Independence, on the other hand, would jeopardize several billion dollars' in investments that major U.S. corporations have in Puerto Rico, and would make life much more difficult for the Puerto Ricans who live half-time in New York.

"Congress and the business interests back commonwealth," Berrios said. "They can do things here that they could never do to a state or an independent country."

Yet commonwealth isn't working right now, and even Hernandez Colon has called for new ideas from his splintered party. Carrion put it best: "People say we want to have our cake and eat it too. But right now we don't even have any ingredients."