A recent Washington Post article sums up Pakistani concerns rather nicely. An excerpt:
Among the Pakistanis' chief concerns are the Obama administration's apparent unwillingness to get involved in the long-standing dispute over Kashmir; the blossoming U.S.-India civil nuclear partnership; and the symbolism of Obama starting his visit at the Taj Hotel in Mumbai, site of the 2008 siege that killed 173 people and has been blamed on Pakistani militants.I have discussed before about Pakistan's credibility gap over Kashmir. It plays a factor why President Obama is not visiting Pakistan in November. As the commentariat correctly states, President Obama is going to India to cement economic deals, including selling defense equipment, airplanes, things a growing economy needs. The United States also sees India has a regional bulwark against an increasingly hegemonic China. Everyone knows Pakistan is China's stooge and a wishy-washy partner in the war on terror.
In essence, what I'm saying is that the United States sees a fruitful relationship with India. Like a married couple, they see a future together. Pakistan, on the other hand, the relationship is mostly a short-term affair. There's no future with an economic basket case like Pakistan. Once the war on terror ends (or, most likely, shift) and the money spigot is turned off, Pakistan will be left in the cold like a jilted lover.
The short version: The United States is not going to divorce India to marry Pakistan.