What excuse does Troy give his wife for his affair?

When Rose asks why Troy needed another woman, his reply is that Alberta was an escape from his responsibilities. She did not have a roof that needed fixing; her house was a place where he could forget that he was someone's husband, someone's father, someone's employee. Troy feels the weight of responsibility so heavily that he can see only endless weeks of labor, endless paychecks to be cashed, endless Fridays blending into one another.