Mr. Green genuinely loves Africa, but he dreams of the "old" Africa during the colonial era, when Europeans had total power and could shape the destiny of the nation. He continually makes cutting comments about Africans, criticizing their inherent laziness, their consistent corruption, and their willingness to make unrealistic demands.
This is quite a mouthful, and it might not be fair to group all of these separate forces into one category of antagonism, but just consider how all of the above affect Obi and contribute to his downfall. These three significant forces together hold Obi to impossible standards. And since he is the first young Igbo man to be in this position, there is no precedent which helps guide him. You could argue that the combination of these pressures puts Obi into an impossibly situation. He lacks the ability to deal responsibly and appropriately with this multitude of pressures, and seems to be unwilling to ask for help.