If you've never read Alice von Hildbrand's book By Love Refined, you simply must. That's all there is to it. It's subtitled "Letters to a young bride," but don't let that stop you even if you can't consider yourself one of those. I first read it a couple years ago, and make it a habit to reread every six months or so. When my roommate recently asked me if I could recommend a good relationship book, I didn't hesitate to lend her my copy. A couple days later, I walked into our room to find her reading sections aloud to her boyfriend. She says it totally changed her view on their relationship, and I've found the same to be true for me and mine.
Every chapter deals with a different aspect of relationships (married, dating, friendship, just plain interpersonal), with practical and down-to-earth advice. Von Hildebrand understands the strengths and weaknesses of women, and how this affects relationships. She's a master of integrating the unique - but certainly different - gifts of men and women, and turning what could be a weakness into a strength. One passage that particularly sticks out in my mind is from the chapter involving those those four "lovely" words that we all know we shouldn't say but somehow can't help thinking: "I told you so."
Alice could have been writing to me personally when she writes,
No doubt when Michael embarks on a hopeless enterprise or is about to make a serious blunder, you must warn him. But if he ignores your warning, you have to let him make his own mistakes. Once the error has been made, your theme changes radically: it's definitely not to stress how wise you were to foresee the catastrophe. It's rather to use your gifts to lessen the consequences of the mishap and help Michael not to lose face. (He should do the same for you when you're the wrong-headed one.)....I highly encourage you to move this to the top of your reading list. Read it all at once, a chapter or two a day, or just pick out the chapters that seem applicable (you certainly don't need to read them in order). At two pages each, a chapter is the perfect length for a quick reminder when you need it.
Objectively there's very little sense in ever saying "I told you so," because by the time you say it, the culprit knows it full well himself.