Many years ago St Paul said much the same thing. He wrote in his letter to the Romans that "I do not do what I want, the very thing I hate is what I do!".
Moral weakness, weakness of will (Greek akrasia) is part of being human. But it also reveals the two central weaknesses of utilitarian ethics and the pragmatism that surrounds our current age.
Maximise happiness or the balance of pleasure over pain: this is the ultimate good, so the argument goes. But it begs the question, why should this be the ultimate good, and, what are the consequences of being a consequentialist?
Suppose I reason that I travel away from home much of the time (I have no idea if this is how Tiger reasoned, I simply use it as an example). I get frustrated without my wife, so as a sportsman, I have a girlfriend in every city. These girlfriends contribute significantly to my success. Back home, my wife knows nothing about it, and I will make very sure she never does. The net effect is that the utility to myself and my various girlfriends (let's assume they are happy with arrangement) is maximised, and the negative effect on my wife is zero.
Unless she finds out. First and greatest weakness of utilitarian ethics is that we cannot know the consequences of our actions, and the law of unintended effects frequently bites us when we don't expect it. I walk into a bar in Melbourne with one of my girlfriends and, oh no, there's my wife's best friend sitting at the bar drinking a Pina Colada. She phones my wife. Suddenly maximum happiness has been converted into maximum pain. And if I'd have foreseen this, perhaps I never would have given into my akrasia.
A second major objection to pragmatic utilitarian thinking is that it destroys my moral integrity. I do things, as Bernard Williams pointed out years ago, like shoot someone in order to save a larger number, which I just can't live with. I may make a calculation but this very calculative method is my undoing. I find I lie or steal or kill or cheat because I falsely think that thinking consequentially is better than following my conscience or a rule (which are both very different approaches).
Aristotle of course would have a moral for this story. He would urge us to work out who or what we want to be in say sixty years time. If faithfulness and integrity are virtues we need in order to be surrounded by our children, grandchildren, and of course our one wife when we are ninety-three, then we should abandon utilitarian ethics in favour of something else. And flourish.