I can't believe we didn't negotiate a peace deal before leaving and with neighbouring countries so that if they breach it there is the threat of military force from them and us (maybe I'm naive to think this was possible) and we wasted all that time and money on training and equipping the Afghan military (poorly it seems) and they just flee, I seem to remember that the same happened in Iraq with their military when Isis was taking over parts of the country. Not providing air support is irresponsible, the Afghan government have asked for this after all.
I am in favour of ending wars instead of letting them drag on forever (and only using war as a last resort, I don't think it's a good way of resolving problems and costs a lot in terms of lives, time and money), but there are things we can do to make sure it's not a disaster and we don't leave them in the lurch.