It is permissible to supplicate to Allah saying "O Allah, make it easy and do not make it hard;" there is nothing wrong in saying that. Both relief and hardship are decreed by Allah (Exalted be He). Allah (the Exalted) said,
And if some good reaches them, they say, "This is from Allâh," but if some evil befalls them, they say, "This is from you (O Muhammad صلى الله عليه وسلم)." Say: "All things are from Allâh," so what is wrong with these people that they fail to understand any word?
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.