I think part of the problem is getting caught up in the idea that airlines are the be all and end all; they certainly pay well, but I found in my own career that the bigger the airplane, the less I enjoyed it. When I started flying corporate, I wondered why anyone would do anything else - it was so nice going to the other side of the airport in a spotless aircraft (and that difference is even more striking post '911). Point is, there are a lot of ways to make a living in aviation, so maybe consider a different lane on the same highway.
If you do quit, I think you'll find flying is a hard game to walk away from - it's got that mystique about it still, "Oooh, you're a pilot?!" Your ego will take a beating, but there are a lot of careers out there that may be more fulfilling for you if you have the courage to leave the "romance" of flying (lol) behind and become a "civilian" again.