Anita Shreve said this quote

A single action can cause a life to veer off in a direction it was never meant to go. Falling in love can do that, you think. And so can a wild party. You marvel at the way each has the power to forever alter an individual's compass. And it is the knowing that such a thing can so easily happen, as you did not know before, not really, that has fundamentally changed you and your son.