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.
I don't think a peace treaty amongst neighbours is even possible. They all pretty much hate each other as much as they hate the West.
I don't know what it is about the Afghan army, but you've clearly got a load of scared young men who are woefully trained, and in effect have been defended from the Taliban by US and allies for the last 20 years. Its hardly surprising that they're getting blown over with a slight breeze. The Taliban don't fear death, they'll just send fighter after fighter at the Afghan army until there's no army left.
I do feel sorry for them. It's also unlikely that the West will do a u-turn and go back to defend them. They're pretty much on their own now.