QWe have two daughters, ages 17 and 13, and I am increasingly concerned about the older one.

She was a happy kid in the ninth grade and part of the 10th grade — busy with school, sports and her social life — and we loved meeting the boys and girls who hung out at our house and the girlfriends who came over for their regular sleepovers.

Her life went down the drain, however, when her boyfriend (her first!) broke up with her. Although her grades were still good, she cut off contact with all of her friends. She also refused to participate in school activities, stayed in her room, ate too much and then wore sweat pants and sweat shirts to hide the weight she had gained. This reduced her social life to zero and made her really lonely, but we couldn’t get her to re-engage.

Last fall, she took an interest in life again and we were delighted. She watched her diet, worked out at the gym, lost weight and made new friends, but she slipped into a funk again, gained back the weight she had lost and broke away from these friends too. They were into drugs and drinking, she said, but I don’t believe it.

Life is very black and white for my daughter. She doesn’t forgive slights, is judgmental, has a volcanic temper when things don’t go her way and criticizes everything her sister does.

(Hadley Hooper/For The Washington Post)

Even though she is responsible with her work, beloved by the kids she babysits (and by their parents too), she is a different kid at home. Talking to her is like walking through a minefield for me, and her dad has only marginally more luck.

I have broached the idea of therapy with her several times, but she refuses to go. I can’t force her to try it, but I don’t want her to be lonely and friendless either.

How can I help this dearly loved daughter navigate the tensions and pressures of her life?

ATiming is everything, isn’t it?

A young woman in graduate school can usually handle a break-up pretty well, even if she’s dumped by someone she loves. Rejection, however, can devastate a young teen if her hormones are raging and her boyfriend has thrown her over in a callous or embarrassing way. Breaking up takes practice, just like everything else.

If your daughter felt that he was judging her — rather than judging their relationship — her brain may have gotten stuck in an emotional pit, much like a soldier who was traumatized by a wartime battle and then developed post-traumatic stress disorder afterward.

Whatever the cause of your daughter’s unhappiness, she needs to get over it quickly, but she shouldn’t do it alone. If one person in the family has a problem, the whole family has a problem, and the whole family should fix it, too.

You can do that more quickly and more easily if you get a therapist to help you examine your feelings, understand each other better and keep the meetings civil and on target. Look for a clinical social worker, psychologist or psychiatrist who is experienced, relates well with teenagers and will include you, your husband and your younger child in at least some of these sessions. This will remind your daughter that she may carry a burden but she never carries it alone.

A nutritionist could help your daughter too, because high school students are more likely to follow the advice of an expert than to follow the advice of mom.

Your daughter is also an expert — at least when she talks about her friends — and you should believe her information too if you can. Although she may — or may not — be exaggerating when she says that she dropped her friends because they drank and used drugs, officials at the National Center on Addiction and Substance Abuse probably wouldn’t be too surprised if they did. According to CASA’s latest report, nearly one out of five teenagers drinks, smokes or uses drugs in or near his or her high school every day; these problems are almost as bad in private schools as they are in public schools.

If your daughter dropped those friends because of their behavior, she did the right thing. Sometimes it’s better to have no friends at all than to have the kind of friends who could lead her astray.

For more advice and news for parents, visit The Post’s new On Parenting page.

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