Libya (and Yemen) has never been a "nation-state" - ever. Libya was always and remains still a vast desert that is home to a loose group of nomadic tribes and two urban centers on the coast in which the majority of the population resides. But those two urban centers - east and west have distinctly different ethnic and cultural histories.
Tripoli and the surrounding area in the west was founded as an ancient Roman port (Tripolitania)and has always looked to Carthage in Tunisia - rich and urbane civilizations.
Benghazi (Cyrenaica) has always looked to Alexandria in Egypt and has always been more conservative.
That fact of geography is at the core of the Libyan dispute and will always be at the center.
Libyans got caught up in the fever of Arab Spring. Just like the other countries in the Middle East,the rebelling masses had outgrown a dictatorship,but just like all of the other states in this region,they had no firm grasp of what they wanted to replace it with. And because of the geography and how it has shaped Libyan society - there just wasn't a critical mass that has the national will to unite and struggle through this period of learning what they want to become.
Each geographical sector instead chose to try and make it's particular tribe the king of the hill. Geography slowly pulls the dynamics of the country back to its natural equilibrium of two competing sides with numerous independent tribes that are not vested in urban western advancement and integrating into the wider world.
And the truth of the matter - on the grand scale of things,Libya has never been a big time player for the west. They have oil,but even that is not as a big factor as it might have been at one time. They affect Italy (and from Italy,the rest of Europe) because of all of the people fleeing Libya by boat to Italy. They affect their neighboring states because the people who went to Libya to find work have returned knowing how to wage war and are well armed and are now causing turmoil back in their home countries. And the chaos is a breeding ground for jihadists,like ISIS. But none of that really ranks up high for America and it's interests.
Libya is a concern for Egypt because eastern Libya has always been drawn to Egypt - but it was never a big problem even for Egypt because there is an impassible desert between Libya and Cairo with only the coast road connecting the two.
Last year,Egypt's President was pushing Libya as a regional and international threat because he is focused on whether the Muslim Brotherhood in Egypt is getting funding and support from Libyan factions connected to Libya's competing Islamist government based in Tripoli. As a result of local Egyptian politics- he wanted everyone to join him in fighting "terrorism" in Libya.
After conducting airstrikes in Libya in Feb.2015,Sisi now says the international community should allow Libyans to decide what government they wish for rather than intervene militarily. This new stance comes just as the west's interest in taking on ISIS in Libya is heating up. The west,through the UN,is working toward a unity government that includes the Islamist sectors in Tripoli rather than choosing one over the other.
So now we have the Libyan elected parliament that is internationally recognized in Tobruk. And it's rival (which is headed by the political Islamist group - Libya Dawn) that has set up a competing government in Tripoli. (when the new parliament was elected,apparently the political Islamist group that dominated the initial interim government refused to accept that secular factions won instead of them).
ISIS has used the chaos to enter the picture and has taken over the city of Sirte on the coast and announced their entry to the party by beheading 21 Egyptian Coptic Christians.
The two competing sides have decided maybe they better sit down and talk to each other. Everyone knows that there is no way these two sides will work together in a unity government. But everyone,including the two competing governments also know that if they don't work together in some kind of capacity against ISIS -they both lose and ISIS gains.
The UN wants the two sides to work together to stop the bloodshed in Libya and is pushing Europe to help stop the conflict there. (not only is there turmoil in Libya,but the thousands of migrants from Libya are flooding into Italy and beyond and are disrupting that region)
But no one wants to get pulled into what is an endless quagmire. Europe wants to help stop ISIS,but only on a limited support basis if Libya's two rival factions get their stuff together.