(Hadley Hooper for the Washington Post)

Q. I haven’t seen or heard from my 25-year-old daughter for five months, and I am brokenhearted. We had always been so close.

Last summer she asked me whether she could move back home after she finished graduate school. I quickly said yes and offered to give her whatever help I could, financial and otherwise, until she could find a job.

After a while, my daughter went into therapy with a social worker and then became very belligerent and argumentative toward me for several weeks. This escalated into an exchange of hurtful words between us, which I feel so bad about because she left right after that and has even blocked my phone number. I don’t understand why she is so mad at me, but I have sent letters of apology for everything I could think of, as well as flowers, gifts, more letters and e-mails, too. I miss her so much.

This break also has affected her siblings. First, my older daughter stopped talking to her big brother, and then my younger daughter politely left home the weekend after her 18th birthday because she said that she missed her sister.

It was my divorce that sent my older daughter into therapy because it went on for three years before the court gave me full custody. In the meantime, their father contested it in ugly, argumentative ways and in front of our three children, so I’m sure it upset the other two children, too.

They never wanted to visit their father after we separated, because he has such a hoarding problem, but my older daughter did move in with him after she left my house (and then quickly moved out because of the hoarding). At some point, however, he apparently told her that I had taken the children away from him, but this couldn’t have been further from the truth. I tried to keep him involved in their lives and even asked him to pick up the children every day so they could see him on a regular basis, but he refused.

The divorce has never ended for him, but all I can think about is the loss of my beautiful daughter. I grew up in a large family and, despite our challenges, I have never experienced a cutoff like this.

A. Your daughter may be acting up because she misunderstood something you did or said; because she realizes that the real world is a lot scarier than graduate school; or because her therapist has somehow encouraged her anger. Unfortunately, some therapists are simply not as good as others.

You’ll never know whether the problem lies with your daughter, with you or with the therapist unless you do some deep digging. And to do that, you need professional help.

The idea of seeing a psychiatrist, a psychologist or a clinical social worker may seem too time-consuming, too expensive or too embarrassing, but there are good reasons to do it.

If you add up the 50 minutes a week you’ll spend with the therapist — and the hours of worry that these visits provoke — the time will seem monumental. But therapy is really a shortcut to happiness when you compare it with the years of tension and the nights of tears you will endure if you let this problem fester.

And yes, psychotherapy is costly, but over the years it will be cheaper than buying a pair of shoes every time you get sad. Psychotherapy is not only better than retail therapy, it can even change your brain scans.

You also may not like the idea of telling your troubles to a stranger, but once you know this person, he won’t be a stranger anymore.

There are caveats, of course.

You need to see someone who is experienced; who is more interested in you than he is in himself; and who is also a family therapist, because you’ll want to ask your children to attend at least some of the sessions. Although your older daughter will probably ignore your invitation, your son and your younger daughter will probably go. Don’t be surprised, however, if their memories differ from yours, because no two people remember an incident in exactly the same way.

These recollections may also be painful for you, but once you hear about the hurts you never knew you caused — and once they hear your explanations — you will all be able to walk in one another’s shoes more easily. These sessions may also inspire your younger daughter to pull her big sister into the family fold again, but don’t reach out to her yourself quite yet. You’ve given apologies, flowers and gifts; it’s time for her to do a little giving herself.

Send questions about parenting to advice@margueritekelly.com.