Analysts say a stalemate, economic and diplomatic pressure, and a growing humanitarian crisis have nudged Abiy toward the table but any talk of peace risks alienating former allies.
Combat in the Tigray region has largely paused since a truce took effect in March. Outright victory is considered all but impossible for both sides, but the status quo has its own issues.
"This peace process is not a sudden development but the result of a months-long standoff that has left both sides with unsatisfactory options," Ben Hunter, East Africa analyst at risk analysis firm Verisk Maplecroft, told AFP.
For the TPLF, the Tigray region largely under their control is suffering a catastrophic shortage of basic supplies, making life extremely difficult for millions.
Convoys bringing emergency supplies into the battle-scarred region resumed in April, but the United Nations says insufficient aid is reaching civilians. Tigray remains under a communications blackout, and deprived of fuel, electricity and banking services.
Abiy, meanwhile, is under intense diplomatic pressure to end the war, particularly from the United States where sanctions are being considered.
Ethiopia's economy is under strain and international assistance is badly needed particularly in the form of drought relief, as a record dry spell prolongs a food crisis.
Inflation in Ethiopia hit record highs again in May with food prices alone climbing 43.9 percent while reserves of foreign currency have evaporated.
"The war is at the heart of the current economic devastation," said Awet Weldemichael, a Horn of Africa security expert at Queen's University in Canada.
International partners are reluctant to inject much-needed foreign exchange into the war-ravaged country, he added.
Abiy also faces challenges away from Tigray.
Federal forces are tied up in Oromia, the country's largest and most populated region, where attacks by the Oromo Liberation Army, a rebel group deemed terrorists by the government, have escalated recently.
This week the OLA, who allied with the TPLF last year, attacked the Gambella regional capital -- the first such strike on a major city by the rebels, said Hunter.
Abiy also confronts rising discontent in Amhara, Ethiopia's second-most populous region, which borders Tigray and backed federal forces when war broke out in November 2020.
Hardliners there want to destroy the TPLF entirely, while others fear Abiy could be settling for peace at the expense of the Amhara people.
"The backdoor negotiations between Abiy and the TPLFdoes not include Amhara's interests, the issues Amharas are concerned about," said Tewodrose Tirfe, one of the founders of the US-based Amhara Association of America.
Their main concern is the status of two fertile stretches of land that some Amharas say was stolen by Tigray in 1991, when the TPLF was at the helm of Ethiopia's ruling coalition.
These areas known as Wolkait and Raya have been retaken since the war began and represented "red lines" that could not be crossed, Tewodrose said.
"If the Amharas do not like are not happy with the negotiated outcome, especially on Wolkait and Raya, then the Amharas will fight him (Abiy)," he said.
Since mid-May thousands have been detained in a sweeping crackdown in Amhara that the government says is targeting criminals.
Tewodrose, however, described those who were rounded up as "dissenting voices" like journalists and students.
Abiy must walk a tightrope to meet TPLF demands without upsetting his erstwhile allies or threatening his own power base.
The TPLF has made the return of western Tigray territory occupied by Amhara and Eritrean forces a pre-condition to a ceasefire.
"Abiy will struggle to persuade nationalists in Amhara to cede control of western Tigray because they claim it is an historically Amharic land," said Hunter.
Meeting TPLF demands for broader political autonomy could also invite similar claims from other regions in multi-ethnic Ethiopia, weakening Abiy's federal power base in Addis Ababa.
As for Eritrea ,the TPLF's historic enemy, and Abiy's ally in the conflict its president Isaias Afwerki "wants to militarily defeat Tigray while weakening Ethiopia, and he will therefore try to keep the conflict hot," said Hunter.
"The risks for PM Abiy are like the risks to anyone who enters a conflict in a team but then unilaterally makes peace with the adversary," said Awet.
"The prime minister, the country and the region are better served if he tries to bring all of his allies to the table with the TPLF (rather) than going it alone now."