The Palestinian cause had already become less central as the region has been rocked by the Arab Spring upheavals
The Palestinian cause has long cemented ties between Middle East nations with divergent interests, but amid shifting regional alliances they are increasingly isolated and in need of new friends, analysts say.
In the latest blow, Bahrain broke ranks and agreed on Friday to open diplomatic ties with Israel, in a deal announced in Washington by President Donald Trump.
Palestinian anger was swift. The deal was "a stab in the back of the Palestinian cause and the Palestinian people" like the UAE-Israel deal announced last month, a top official from the Palestinian Authority told AFP.
At a summit of the 22-member Arab League this week, foreign ministers failed to back a Palestinian push to condemn last month's US-brokered normalization deal between Israel and the United Arab Emirates.
"May you never be sold out by your 'friends'," read one bitter tweet by senior Palestinian official Hanan Ashrawi after the UAE-Israel deal was announced in August.
With the accord set to be signed on Tuesday at the White House, the Emirates will become only the third Arab country, after Egypt and Jordan decades ago, to establish full relations with the Jewish state.
In a statement Trump tweeted about the Bahrain-Israel deal, he revealed Tuesday's signing ceremony would also be attended by Bahraini officials.
The UAE has defended its move in part as a way of halting Israeli Prime Minister Benjamin Netanyahu's proposed annexation of settlements in parts of the occupied West Bank.
The Israel-UAE deal "suspended" those annexation plans -- but Netanyahu has insisted they are not off the table in the long run.
Despite this, the Palestinians' traditional Arab allies have either welcomed or silently endorsed the normalization agreement with the US and Israel voicing hope more Arab states would follow suit.
'Deteriorating Arab unity'
"The leadership is very upset," said Sari Nusseibeh, a former top official with the Palestine Liberation Organisation.
"But I don't think they are more upset than in the past about the Arab world in general. Palestinians have always complained that the Arab world has not stood behind them as they should have."
The Palestinian cause had already become less central as the region has been rocked by the Arab Spring upheavals, the Syria war and the bloody reign of the Islamic State jihadist group.
At the same time, hostility has deepened between US ally Saudi Arabia and Iran, its Shia Muslim rival which supports proxy forces from Syria to Lebanon.
"There have been all kinds of problems in the Arab world -- disputes, revolutions, civil wars, tensions between different Arab countries," said Palestinian analyst Ghassan Khatib.
"Palestinians are now paying the price for the deterioration in Arab unity."
Ramallah maintains the validity of the so-called "Arab consensus" and rejects the notion that it is isolated.
That consensus has long held that Arab states will only normalize ties if Israel meets a number of conditions.
One demand is for Israel to withdraw from the territories it occupied in the Six-Day War of 1967.
Another is to agree to a Palestinian state with east Jerusalem as its capital, and a third to find a just solution for the millions of Palestinian refugees and their descendants.
"We hope that the Arab countries will remain committed to this consensus," said Jibril Rajoub, a senior Palestinian official, "adding that straying from it "will lead to nothing".
"Those who are violating the Arab consensus ... will be isolated" in the long term, he warned.
One Western diplomat, speaking on condition of anonymity, shared the view that at the moment "the Palestinians don't really have a way out, they are stuck".
"They are also stuck because of those who want to support their cause, whether it is Turkey or Iran."
Iran already has relations with armed Islamist groups in the Gaza Strip, such as Hamas and Islamic Jihad, and slightly cooler ties with the Palestinian Authority.
The Palestinian cause has also received backing from Turkey, a regional power increasingly at odds with Israel and which militarily backs a rival faction in the Libya war to the UAE and Egypt.
"Turkey does have an ambition to lead this cause and is pointing to the hypocrisy of both Arab states and the West for not emphasizing this issue enough," said Gallia Lindenstrauss of Israel's National Institute for Security Research.
Rajoub insisted: "We are not ignoring any country. Turkey is a regional superpower, it's an Islamic country and we are on good terms. We'll keep cooperating with everybody."
But analyst Khatib argued the Palestinians should keep their distance from Turkey, Iran and also Qatar, which is deeply at odds with other major Gulf powers.
"It's not wise for the Palestinians to be caught within the regional tensions and competition between regional superpowers," he said.
"If you side with Iran, you'll lose Saudi Arabia. If you side with Turkey, you'll lose someone else.
"It's better for the Palestinians to keep a safe distance from these different regional superpowers."