Why did Italy refuse to honor its treaty obligations to Germany and Austria

Italy's main issue was it's enmity with Austria - Hungary, Germany's main ally. Which made Italy like the odd man out in the so called triple alliance between the three of them. Italy had only joined out of fear of France.

Answer: Italy's main issue was its enmity with Austria-Hungary, Germany's main ally. That made Italy the "odd man out" in the so-called Triple Alliance with the other two.

Italy had joined with Germany out of a fear of France. This occurred when France and Britain concluded an alliance that made Britain responsible for the mutual defense of the English Channel, and freed the French fleet to concentrate in the Mediterranean, possibly against Italy.