The difference between deep-rooted love and allegiance, and mutual cooperation and assistance, is major.
Mutual cooperation with the kuffar (in that which is clearly a benefit to the Muslims) and interaction with them is permissible by consensus. Indeed this occurred during the time of the Prophet (sallallahu alaihi wa sallam) as there were Jews and hypocrites in Medina, and the Muslims interacted with them. However - allegiance, deeprooted affection, and love is something else beyond that.
It is obligatory to differentiate between the two affairs so that a person does not have evil thoughts that what occurs (of mutual cooperation between a Muslim and Kafir, or Islamic Country and Non-Islamic Country) is from allegiance and love (when in reality it is not).