There is very little loyalty in this industry and I agree with the other posts. Do what is right for you not what you think your company would like of you. You only work for them, they are not your life masters!
If it makes you feel guilty leaving, then remember this (you are releasing a vacancy for a wanabee who wants to join your present airline). I personally wouldn't leave under any clouds (ie paying my bond back).
If you entered a contractual agreement then I think it should be honored as you accepted the terms in good faith when you signed up. Anyway, the industry is still a small place....... if you catch my drift!!
Good luck with whatever you decide
FJ