I couldn't stay mad at him for his kleptomania (which unfortunately extended beyond his relationship with me), because I somehow understood that it was his way of dealing with the inequality between our family's financial situations. Now, I often complained about how we didn't have enough to get everything I wanted, but being with my friend helped me realize just how well off my family was. To my friend, I had more toys than any person could play with at one time while he had very few. It wasn't theft to him if the person didn't notice it was gone or had the means of easily replacing it. People who had more or who didn't full appreciate what they had deserved to have their things taken from them.
Our relationship made me recognize just how good I had it (although understanding did not affect my behavior), but it also helped me understand both the unfairness of our social system and why people feel stealing is justified. In a sense, my friend was right. I hadn't done anything more than he did to deserve the better lifestyle that I enjoyed.
Unfortunately, there are many people in the world that believe that stealing something that they believe the owner won't miss is justified. These people don't just steal items, though, they steal other people's health and time. Our economic system is based on how much a business can "steal" from its employees in "cost saving measures." Sure, there is an agreed-upon wage, but that itself is based on the worker not fully understanding (or being able to do anything about) the unfairness of the transaction. Money itself is valueless, but is exchanged for the priceless commodities of health and time.
I know that there are resources in the world that are finite and that there will always be an unequal distribution of them, but that doesn't mean we shouldn't take steps to reduce the inequality in our world. My friend may have stolen from me, but I realize that I should have given him more.