|Advancing in the wrong direction|
The Libyan opposition has been voicing its frustration with NATO for unloading an insufficient tonnage of bombs, though the bombs that were unloaded were quite sufficient to kill civilians, children included, and opposition fighters themselves. Meanwhile intervening powers are no doubt equally frustrated with the opposition seeing it has been losing ground to the government which now looks well positioned to advance on Benghazi. A defeat of their clients would deal a blow to the prestige of the intervening powers.
Opposition fighters are not terribly accomplished at waging war to say the least, but more than that they have very little incentive to become better. The most straightforward way for them to win is to secure for themselves a still wider foreign intervention and have NATO do their fighting for them. In bringing about this goal loosing ground is much more useful than gaining ground, since it brings pressure on the foreigners to "do something" to change the situation. Still greater amount of pressure is brought to bear by playing up the extent of civilian suffering caused by government forces (the suffering caused by themselves and NATO is naturally ignored) and accusing foreign powers of a lack of empathy.
NATO for its part has for the umpteenth time demonstrated its impotence. The government forces quickly adapted to the new realities, switching dated tanks for technicals and unmarked cars making themselves difficult to readily distinguish from the opposing forces, and are now once more giving chase to the opposition. At the end of the day the air force is little more than a rich man's car bomb. It can destroy, kill, wreak havoc, but it can not sweep away the enemy and it is never certain it can compel it to capitulate. The idea regime change can be accomplished from the air is about as credible as the idea a revolution can be brought about by bombs planted by terrorists.
Certainly it is within NATO's ability to unseat Gaddafi, but not without risking casualties of its own - something it is historically extremely loathe to do. Killing for "humanitarian" purposes, has always held more allure for NATO forces than dying for them. In 1995 in Bosnia a workaround existed, Croatian Army could be made to intervene against the Bosnian Serbs on the behalf of the Sarajevo government. Thanks to media demonisation of the Serbs, during the 1999 bombing of Yugoslavia NATO could get away with going after civilian targets. This time given that Libyan opposition does not seem to be up to the task and that intervention has been ostensibly launched on behalf of the long oppressed Libyan people, rather than against it, it is a different story.