DEAR ABBY: I have been faithfully married for more than 20 years. My wife and I are known as the "cute couple" who still hold hands in public, take time to play together, and never say a negative word about each other in public.

My son, who has just turned 19, wants to marry somebody "just like Mom," whom he views as the world's greatest wife and mother. He's making good on this and has begun getting serious with a young woman who is much like his mother in many crucial ways.

At this point, how do I tell my son that the biggest mistake of my life was marrying his mother, and his future happiness depends on getting away from this girl before it's too late? The girl he is dating shows the same severe anxiety disorders as my wife, and manipulates him through learned helplessness and (presumably) the same psychosomatic chronic illnesses. She displays the severe mood swings that have made my wife completely ineffectual as a mother and companion.

My wife's disorders completely dominate our lives, as she refuses any therapy. I have had no choice but to surrender and make do, abandoning a wonderful career -- Ph.D. from a top business school, lots of international travel and high ambitions -- to live in squalor and relative poverty, hating my life and longing for the freedom that will come from one or the other of us passing on.

I have done a good job of hiding my agony from my wife and children, accepting that which I cannot change, and I have been careful to be as supportive as possible and never undercut her position in her eyes or the kids'. My son shows the same potential that I once had. How do I help him not ruin his life as I have ruined mine? -- MISERABLE IN THE NORTHEAST

DEAR MISERABLE: First, remind your son that marriage should be postponed until he completes his education. Then realize that although you want to help him avoid the disappointment and frustration that you have experienced, you may not be able to save him after keeping him blindfolded all these years.

A giant step in the right direction would be to sit him down and tell him exactly what you have told me. And when you do, point out that because you did not confront the problem and insist that your wife get treatment for her emotional problems, you became her enabler, because in addition to her illness, your failure to intervene is what ruined your marriage.

DEAR ABBY: I have an etiquette question. When going out for an office luncheon in honor of someone's departure, new hire, baby shower, etc., and the boss is picking up the tab, is it proper to order what you really want from the menu?

For example: If six people at the table order soup and salad, but what I really want is the salmon stuffed with crabmeat, would that be considered improper, even though the boss says, "Order whatever you want"? -- KAT IN WASHINGTON, D.C.

DEAR KAT: Usually when a host treats guests to lunch, he or she will set an example by saying, "I'm having the ( ), but feel free to order whatever you'd like." If the entree the boss selects costs $15, then the polite guest should stay within that limit.

For an excellent guide to becoming a better conversationalist and a more attractive person, order "How to Be Popular." Send a business-size, self-addressed envelope, plus check or money order for $6 (U.S. funds only) to: Dear Abby Popularity Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included.)

DEAR ABBY: I have been married to the same woman for more than 30 years. My wife has recently been diagnosed with cancer. During all the years of our marriage, I blocked out everyone else because I thought all I needed was her. Now my biggest fear is that if I should lose her, I'll be completely alone. What in my personality caused me to do this? -- REGRETFUL IN LOS ANGELES

DEAR REGRETFUL: It's possible that your wife has fulfilled all of your needs for companionship during your marriage -- and/or you may not be a particularly social animal. Please don't waste your time looking backward and feeling bad about what you "should" have done but didn't. So many advances have been made in the treatment of cancer; your wife could survive to spend many more happy years with you.

If your fear is that, in the event of your wife's death, you will face a bleak and solitary future, please realize that eligible widowers in your age bracket are highly desirable. Rather than worrying about being socially isolated, worry more about holding the "casserole brigade" at bay until you're far enough along in the grieving process that you don't get involved too quickly.

DEAR ABBY: I'm a divorced woman with two grown children. My daughter is 24; my son is 19. I am a professional firefighter and in excellent shape. I recently met a man at the gym, and we were mutually attracted. He's a firefighter in a nearby city, and we have mutual friends. There has been some discussion about going on a date, but so far nothing has transpired.

The problem, as my daughter sees it, is that he's 16 years younger than I am and one year older than she is. She's upset by the age difference and says it is "disturbing." My fiance died suddenly two years ago, and I have only recently begun dating again. I asked her to be happy for me. She responded that she thinks it's great that I'm pretty enough and in good enough shape to attract a 25-year-old, but it's "not right."

I love my daughter, but I don't want to live my life to make her happy anymore. She's an adult. Neither of my kids lives at home. I see them about once a month or so.

My daughter has discussed this with her friends, who all side with her. Because I work with men, I threw the ball into their court. They all said, "Great! Go for it!"

Why can't my daughter be happy for me? She would rather I date someone in his 40s -- and I would, if I met someone who showed any interest.

My profession is a difficult one for the average man to accept. They don't like the fact that I spend so much time around other men. I feel as though my daughter is turning this latest dating interest into something lewd and tawdry when it is far from it. What should I do? -- TINA IN TEXAS

DEAR TINA: Understand that your daughter may feel threatened because you are drawing from the same dating pool that she's fishing in. Then decide that if that man finally asks you out, you're going to live your own life and keep it private. From my perspective, too much conversation has already occurred. You have been put on the defensive, but you don't owe anyone an apology.

What teens need to know about sex, drugs, AIDS and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-sized, self-addressed envelope, plus check or money order for $6 (U.S. funds) to: Dear Abby -- Teen Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in the price.)

DEAR ABBY: May I please respond to the letter you printed on Oct. 29 from the seventh-grader whose stepmother refuses to wear a seat belt? I, too, was careless about using my belt when shoulder-strap seat belts were first available.

At the time, I worked for an insurance company, and one of the claims adjusters pointed out that when a car is going 55 miles per hour, the passengers are also going 55 miles per hour, and if "something" should suddenly stop the car, you are STILL going 55 miles per hour until the point of impact. Needless to say, I never failed to wear my seat belt after that. -- LORI IN ARNOLD, CALIF.

DEAR LORI: Thank you for the reminder. I hope the letters I am printing today will be a wake-up call to the careless and the stubborn. Read on:

DEAR ABBY: As a retired chief deputy coroner for Madison County, Indiana, it was my duty to investigate automobile fatalities. The No. 1 contributing cause of automobile deaths was and still is the deadly head-on collision. When two cars traveling 45 miles an hour are involved in a head-on collision, their total speed at impact is equal to 90 miles per hour. The victim is either thrown through the windshield or free of the car and killed instantly when the automobile crushes him.

Head-on collisions happen without warning: Another car crosses the median or center line, a tire blows out, someone was driving under the influence of alcohol or drugs.

The reason for buckling a seat belt is to prevent making contact with the windshield and to keep the passenger inside the vehicle. When this is done, your chances of survival are far greater if you're involved in a head-on auto accident. -- DONALD G. McGRANAHAN, VERO BEACH, FLA.

DEAR ABBY: I didn't buckle up either, until about 14 years ago. It took being in a serious car accident to convince me to always buckle up.

My injuries were numerous, including 90 stitches in my face. I have the scars as a daily reminder. To this day, I still have eye problems because my eyeball was pushed back upon impact. I had a fractured skull and a closed head injury, but fortunately, no permanent damage there. But I spent three weeks flat on my back.

How humbling it was to be carried to the tub to be bathed, and to be slid off the sofa and onto a bucket to go to the bathroom. I was not able to work for three months.

I admire that seventh-grader who wrote about his concern for his stepmother. As a stepmom myself, I would happily and cheerfully comply with a request to buckle my seat belt and count my blessings. -- LEARNED MY LESSON IN PENNSYLVANIA

DEAR ABBY: My accident happened when cars were built like Sherman tanks, and seat belts were not required by law. I was seated next to my husband, who was driving.

We were hit head-on by a drunk driver. I broke the windshield with my face, and I was stuck in it by a shard of glass up under my chin. Both my legs and hips were broken in numerous places from the impact and the seat being thrown forward, and I have required numerous surgeries since. If you think my experience will serve as a warning to others, please print it. -- MARJORIE H.

DEAR MARJORIE H.: Here's your letter. Now let's cross our fingers.

Abby shares more than 100 of her favorite recipes in two booklets: "Abby's Favorite Recipes" and "More Favorite Recipes by Dear Abby." Send a business-size, self-addressed envelope, plus check or money order for $12 (U.S. funds)

to: Dear Abby -- Cookbooklet Set, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in price.)