A friend and I once talked about how one could still believe after having been deceived over and over again.
In her opinion, if you still choose to believe after so many times, it seems that it is more like, after all, your own problem rather than the cheating one's. Take her father for example. Being the eldest son in the family, he always feels responsible to take care of all the family members, including two gambler brothers and their families. Well, not very surprisingly, these two gamblers took as much advantage as possible of their big brother. But lucky to his father -- I am very very sorry to say that-- one of her uncles committed suicide. And the other uncle, who used to be the owner of a factory and a millionaire, became a scumbag and basically lives for tricking a small amount of money, like couple thousands, out of his brother or sisters' pockets. As a result, my friend's father has caused his family numerous troubles, for he not only paid off the debts of his brother's but borrowed money from the bank, or even from the loan sharks, to meet his brother's needs.