The events and future of Pakistan and Afghanistan are intertwined, if you havent learned this by now, your bound to make the same mistake again.
The border between the two countries is inseperable. People move freely between them and the terrain is next to imposible to patrol let alone control completely. There so much intermarriage across this border, that people travel back and forth on a daily basis. With the arrival of some 5 million Afghans to Pakistan, a large number of them have intermarried into Pakistan with people of all of Pakistan's province. If history is any indicator, the two regions (Pakistan and Afghanistan) are always connected, turned into one in some form or another.
We should be building bridges, roads, infrastructure, railways to link and integrate Afghanitan's eastern and southern regions with Pakistan. Pakistan is a country soon to cross the 200 million mark in population, their future lies with us. The investments we are doing in Afghanistan are also in our interest, india's role and attempts to gain influence in afghanistan are short term acts to cause chaos and exploit poor Afghans to commit terrorism both on their own people and the people of Pakistan will not last long.
There will never be peace with india, as long as Kashmir is forcibly occupied by them and a plebiscite is not held. That is our principal stance.
If anything, a wall needs to built on our eastern borders, and there should not be any trade, commerce at all until the Kashmir issue is resolved. This should be a principal stand.
In the end of the day, Pakistan and Afghanistan are brothers, and we must realize that events in either country affect the other. Our future lies together, an astute student of history would know that, so please dont limit yourself and think in tunnel vision. Furthermore, Afghans stability and economy will directly increase Pakistan's through which nearly 80% of its commerce travel through (despite attempts and projects by india to build roads to divert this trade)
Afghanistan just came out of 30 year of war, its government is shaky, infiltrated and subverted by elements encouraging hatred against Afghanistan's neighboors, ironically countries with which its future lies with and can only progress with. The irony, is the Pashtunistan issue itself is a NO Brainer, The Persian/Dari dominated beauracracy itself would never allow it. Infact they where the first ones to balk and kill the Pashtunistan movement on its own. Furthermore, Pashtuns themselves, while they may talk about it, there is no basis for such a nation nor is their any history of a Pashtun-only nation, Pashtuns have always lived in a multicultural nation alongside Tajiks, Panjabi's and Baloch etc... And if you understand the Pashtun psyche, can you even imagine a Pashtun only nation... lol
Pakistan and Afghanistan, despite all the propoganda, are brothers, and the people are like family. Our destiny and future is one, to think otherwise will result in failure. Pakistan's presence and investment in Afghanistan is akin to Pakistan investing into its future, we must do it..!