Washington — Richard Fairbanks, America's man behind the scenes at the Lebanon reconciliation talks, is reported to be tired of the Middle East's intractable conflicts.
So tired, Mr. Fairbanks told one associate, that ''I don't ever want to set foot in the Middle East again.''
Fairbanks has worked for more than a year as a special Middle East peace negotiator for Secretary of State George P. Shultz. His most recent immersion in the Middle East involved helping to arrange Lebanon's current cease-fire alongside Robert C. McFarlane, President Reagan's special Mideast envoy. Mr. McFarlane has since moved on to become Reagan's national-security adviser.
In the early stages of the search for a new chief Middle East envoy, Fairbanks was one of the people considered. But it quickly became apparent that the lawyer-turned-diplomat did not want the job. The White House decided in light of the bombing of the US Marine headquarters in Beirut that it needed a more prominent figure than Fairbanks as chief negotiator.
That more prominent figure is former Defense Secretary Donald Rumsfeld, whose appointment was announced by President Reagan on Thursday. Mr. Rumsfeld, a one-time all-Navy wrestling champion, is expected to have the stamina to grapple with Middle East demands that have worn down many a man before him, including Fairbanks and former chief envoy Philip C. Habib. But does he have the slightest chance of facilitating a peace in Lebanon or, for that matter, a settlement of the Arab-Israeli conflict?
The answer from US State Department officials to the latter part of this question is a very tentative yes. These specialists see a glimmer of hope in two new developments:
* New signals from Jordan's King Hussein that he might be willing to join the ''peace process'' under certain circumstances.
* A further decline in the fortunes of PLO chief Yasser Arafat.
In Geneva, meanwhile, small signs of progress were reported from the opening of the Lebanon reconciliation conference. On Wednesday, the conferees agreed to define Lebanon as Arab in identity. Agreement also seemed possible on proposals to freeze implementation of the US-mediated security agreement signed May 17 by Israel and Lebanon. But more difficult issues, including the redistribution of political power in Lebanon, have yet to be resolved.
At the same time that it works on the Lebanon problem, the Reagan administration wants to revive President Reagan's Sept. 1 peace initiative of last year and work toward a broader Arab--Israeli peace. Donald Rumsfeld will be faced with both these tasks.
A State Department official said that an opening for Rumsfeld may develop on the broader front, because Jordan's King Hussein has been ''making noises'' about joining the negotiations. Last spring, Hussein backed away from this prospect because of Yasser Arafat's disapproval as well as opposition from the Syrians and other Arabs. But Arafat's position has further deteriorated since then, leaving some officials to conclude that there is a chance of getting other Palestinians involved in the process.
According to United Press International, Syrian and Palestinian tanks and artillery on Thursday bombarded two refugee camps outside Tripoli, Lebanon, in a full-scale assault on Arafat's last strongholds. The PLO leader's forces had earlier been driven from the Bekaa Valley after dissident PLO guerrillas mutinied against Arafat's leadership.
''Does Arafat represent the Palestinians?'' a State Department official asked earlier this week.
One specialist said some administration officials believe that a number of Palestinian leaders on the Israeli-occupied West Bank of the Jordan River could be persuaded to bypass Arafat and join forces with King Hussein. But he said that other officials contend that there is still a chance for an Arafat-Hussein agreement on peace talks with Israel which would allow Arafat to find a new home in Jordan.
Rumsfeld's appointment as Middle East envoy was welcomed at the State Department. Secretary Shultz had earlier proposed that Rumsfeld replace William P. Clark, recently named secretary of the interior, as President Reagan's national-security adviser. But some conservative supporters of President Reagan, who have been unhappy with many of his top-level appointments, saw the Rumsfeld appointment as merely one more sign that the administration is now dominated by moderate Republicans who had served under Presidents Nixon and Ford.
Rumsfeld, currently chief executive officer of the G. D. Searle & Co., a pharmaceutical company, was director of the Office of Economic Opportunity under Nixon and White House chief of staff and defense secretary under Ford.
''This is the Ford administration without Jerry Ford,'' said Richard A. Viguerie, publisher of Conservative Digest. ''Not very many who fought with Reagan in the trenches have been appointed to this administration. . . . All the Nixon-Ford retreads are back again.''