Unfortunately the U.S. did not respond to Lebanon's calls for military help in the 60s and 70s for protection from the Syrian/Israeli conflict. Eventually the country disintegrated and the population fled until the 80s when the U.S. finally sent too few troops too late to do any good, and for the wrong purpose. The rapid withdrawal over the first American casualties left a worse mess than it found. The country has been broken into factions that will not be resolved as a whole until foreign involvement by countries interested in instability in the region ceases and the Lebanese have some chance to rule themselves, instead of worrying over a Syrian takeover.
Many Lebanese started fleeing the country in the early part of the 20th century, and the flight has increased with the instability. I don't really see a solution, nor a way of avoiding another civil war, without a large military presence willing to fight both Syria and Israel to remove their involvement. I can't think of any neutral army that could do this properly. China has the neutrality and the military, but not the ability to deal with all parties in a diplomatic effort to cease hostilities. Russia and the U.S. can not be neutral, yet they do have the military and diplomatic resources.
I feel sorry for everybody in the region as most of what they are seemingly fighting over is rooted in their history, and none of the sides can trust the other at all.
Lebanon is now home to Syrians and Palestinians, and with three separate groups (or more) trying to gain control, civil war seems inevitable.