Why did the League of Nations fail from the three international relations perspectives?They are: realist, liberal and identity.
Realists would say that the League failed because things like that will always fail. States will pursue their own interests rather than wanting to help others in the way that the League would have wanted them to.
Liberals would argue that it failed largely because it did not have time. Organizations like the League cannot prevent war immediately. Instead, they are more likely to promote peace in the long term by encouraging peaceful interactions between various countries.
People who focus on identity would argue that the League failed because not enough countries identified with one another. The French, for example, did not identify with Ethiopia or with China and therefore were not willing to do anything to help those countries when they were invaded.