There’s been a lot of reflecting about Princess Di as the 10th anniversary of her death and the premiere of “The Murder of Princess Diana” fast approaches. Despite her privileged upbringing, beauty, wit and grace, she had the same relationship problem that “normal” women have — many times she thought she had found a prince, but he turned into a frog.

Fortunately, we common folk can learn a thing or two from Diana and other members of the ruling class (besides how to wave from a horse-drawn carriage). Relationship expert Daylle Deanna Schwartz, author of “All Men Are Jerks: Until Proven Otherwise: A Woman’s Guide to Understanding Men,” explains how you can steer clear of court jesters and reign for life as the queen of hearts.

Royal Couple #1: Charles and Diana
Problem: He still carried a torch for his ex.
Common Folk Solution: Charles and Di were doomed to divorce before their 1981 marriage even took place because he was still in love with his ex, Camilla Parker Bowles. Diana knew Charles’ affections lay elsewhere but hoped that in time her soon-to-be spouse would forget all about his last ladylove. Don’t make the same mistake Diana did. If your beau yearns for an old flame, don’t say “I do.” “Women are often so anxious to have a relationship that they put on the blinders,” says Schwartz. If you suspect your man hasn’t recovered from his previous relationship, your first step is to control yourself — don’t give him a “her or me” ultimatum. “You can’t tell someone to turn off their emotions,” Schwartz says. “The ultimatum will just make him more possessive about his feelings for the other person.” Instead, Schwartz advises women to stay busy and enjoy themselves. “Show him he’s got to compete for your time, instead of giving him the impression that you’re there anytime he wants you,” she says. “This will make him think less about the other person — if he really cares about you, that is.” If he doesn’t care, then leave him behind. Why waste your future on someone who’s hopelessly stuck in the past?

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Royal Couple #2: Prince William and Kate Middleton
Problem: He won’t commit because he wonders whether she fits his lifestyle.

Common Folk Solution: “Wills” and Kate have navigated some rough waters since they hooked up in 2003. Although their love boat hasn’t struck an iceberg yet, it hasn’t exactly sailed off into the sunset, either: They’ve lived together, were reportedly engaged, split up and, according to some reports, are now seeing each other again. “I think he’s frightened by what marrying a prince did to his mother,” says Schwartz. “He probably wants to make sure the person he chooses can handle his fame and lifestyle.” Your man may not be as famous or rich as William, but he may have the same concern. “Men tend to want to keep their lives the way they are, which leads to commitment-phobia,” she says. “They worry, ‘Will I have to change too much for this woman?’” The answer? You need to fit into each other’s lives. When it comes to making changes, “women work much too hard,” says Schwartz. You need to accept all aspects of his lifestyle — including his late nights out with the guys. Likewise, he has to accept your lifestyle, from all-day gabfests with your gal pals to your occasional cleaning frenzies. If your guy just can’t decide whether your lifestyles mesh, try Schwartz’s strategy. “Explain that you’re looking for commitment, and then give him a long deadline — at least six months,” she says. “Be really clear. Tell him, ‘I’m going to stick around until the deadline. But at that point if you’re not sure, then I’m going to end it.’” Mark the deadline on the calendar if you want, but never mention it again until the day arrives. If you do, he’ll just get defensive. “Just go out and have the best time you can during those months,” says Schwartz. At the end of six months, it’s decision time. “Sweetly say, ‘OK, the date is here, are we going somewhere or not?’” If he still can’t answer, move on.

Royal Couple #3: Fergie and Prince Andrew
Problem: A long-distance relationship was too hard to handle.
Common Folk Solution: Just weeks after his wedding, Prince Andrew shipped off with the Royal Navy for five years. Fergie has said his departure left her devastated. It also left her in the arms of a few other men while Andrew was away. Before you get too involved with someone who’s destined for a different time zone, Schwartz suggests that you ask yourself some tough questions: What am I going to do when he’s away? Can I cope with long nights? Do I have a support system of friends? If the answers to these questions leave you feeling uneasy, find a man in your zip code.

Royal Couple #4: Prince Albert of Monaco and his revolving door of lovely ladies
Problem: One woman just isn’t enough.
Common Folk Solution: We’ve all encountered players at some point. They may not be as worldly as Prince Albert — heck, some of them rarely cross the state line. But their similarities cross class lines. Says Schwartz, “They’re really hot, really spoiled and women tolerate their crap.” Think you’re “the one” who can get him to ditch his little black book for a house with a white picket fence? Think again. Schwartz says, “Women tell themselves, ‘But he’s never been with someone like me.’ That’s exactly what a player wants you to think. Rather than one woman pleasing him, he’ll have 12, and each is bending over backward to prove she’s the one he can’t live without.” Still want to date him? Fine, just don’t be delusional. Playboys, with rare exceptions (think Warren Beatty), never settle down. “Put your needs first,” Schwartz says. Make plans with your friends or with yourself, whether it’s a home spa treatment or a movie marathon night — and don’t break those plans when he finally calls. “Don’t just say you’re busy. Be busy,” Schwartz advises. And last but not least: Practice safe sex. When you’re dating a guy who gets around, you’re sleeping with all the women he’s sleeping with.