In truth, Netanyahu is using the partisan divide between Democrats and Republicans in order to pressure Democrats to increase their support for Israel, even if Israel needs criticism for its crushing mistreatment of the Palestinian People. The Israeli government has done this for decades. If they had not been so successful at it, the United States would have long ago scolded Israel for its hardliner policies toward the Palestinians. In turn, Republicans are using Netanyahu to discredit President Obama and members of his Party, because many Republicans continue to live in that would where criticism of Israel can cost people their jobs and lead to unrelenting political backlash.
That said, hurt feelings have nothing to do with the controversy surrounding Netanyahu’s speech. In fact, the speech has little to do with US foreign policy concerning Iran’s nuclear program. Should Israel manage to derail negotiations with Iran, Iran will move to aggressively pursue the development of nuclear weapons. Should Iran reach a nuclear deal with the United States and the rest of the West, which Israel feels is a bad deal, Israel has the choice to sabotage Iran’s efforts or launch a unilateral attack. While the latter scenario leaves Israel to act against the rest of the world with whatever backlash may follow, it does open the country of Iran up to increased Western intervention, i.e. increased scrutiny.