(CNN) I'm often asked when couples should consider therapy. It's common for one partner to be unhappy, feel disconnected or feel that their needs for intimacy aren't being met.

But rather than communicate about it, that partner may open up a metaphorical window with someone else and begin an affair. By the time the couple comes to therapy, the affair itself becomes the main topic, and its underlying causes are often ignored.

The same scenario rings true for other sources of contention, from financial disagreements to sexual concerns. It's clear that couples shouldn't wait until they're in crisis mode to come to therapy, but what should they do?

When is the right time to see a therapist?

Couples should seek therapy long before they think they "need" to. Most experts believe that therapy can be an important part of your relationship. "Most issues within a couple start small and then grow in size when they don't get resolved. This is where therapy can help, by giving tools and techniques to improve conflict resolution," explained Kristie Overstreet, a licensed mental health counselor. "The majority of couples that I work with say that they should have started therapy years earlier."

"There are three sides to every story: his side, her side and the truth," psychotherapist Kimberly Resnick Anderson agreed. "An objective third party can be just the ticket when couples feel they can no longer communicate effectively."

Rather than viewing therapy as the solution to a crisis, look at it as an integral aspect of a healthy life, suggested Ashley N. Grinonneau-Denton, marriage and family therapist.

"Every couple should take preventive measures to maintain health in their relationship, just like going to the gym," she said. "If couples don't work their relational and emotional 'muscles,' they become un-toned, weak and create more of a chance of damage being done to their relationship."

What happens during couples therapy?

Although every therapist is different, there are some commonalities. The first session typically involves the therapist getting to know you, discussing the areas of the relationship they hope to improve and setting goals.

Some, but not all, therapists will assign homework for the couples to work on before the next session. "Ideally, most of the work gets done, in my experience, outside of my office," psychotherapist Samantha Manewitz said.

What problems can benefit from therapy?

Couples come to therapy for any number of reasons, but in my experience, in addition to infidelity, the greatest issues include sex, communication, money and major life changes such as getting married or starting a family. Couples therapy is also a good idea if one of you is coping with an issue that might be affecting your relationship (such as depression) or simply if you're feeling stuck and stagnant in your relationship.

Therapy can provide a safe space to talk about sensitive topics such as sex. "Just like folks can get caught in a negative relational cycle, couples can often also get stuck in a negative sexual cycle," said Michael Moran, a certified sex therapist. "I tell couples that when the sex they're having is worth having, they'll have more of it. And so we need to explore what blocks exist to creating that place between them."

Communication is also a big concern for couples. But simply talking with each other more isn't the answer. "There is communication, and then there's effective communication," explained Sara Nasserzadeh, a psychologist. "Both parties need to feel heard, soothed, respected and cared for first. We analyze old communication patterns and then replace them with feasible and more effective ones. These are all worked out collaboratively with the couple and within the context of their everyday life."

You might also consider couples therapy to help support you at times of major life change and transition. "Getting married, becoming parents for the first time, moving, changing jobs, losing jobs, becoming empty-nesters, coping after extramarital affairs, recovering from addiction, caring for aging parents -- all of these transitions can destabilize a couple's equilibrium," Anderson said. "Therapy affords couples an opportunity to negotiate these transitions with as little disruption as possible and to explore and honor what a particular transition means to each partner."

And don't discount the value of couples therapy in helping you and your partner dig yourselves out of a rut.

"Therapy allows couples to talk through their feelings and articulate how their relationship may not be meeting their expectations," said James C. Wadley, a licensed counselor. "More often than not, there is some common ground that may have enabled them to be in the relationship. 'Feeling stuck' can shift if both parties are willing to compromise in a way so that individual needs are met."

What if one partner refuses to go?

This is a fairly common scenario in couples therapy. How you approach it can make a difference. "Talk with your partner extensively about why you're feeling you'd like to get into couples therapy," Moran said. "Don't just spring it on them and insist they go."

If they're still hesitant, remember that you can attend therapy on your own. This alone may have a beneficial effect.

"Instead of waiting for the other person who doesn't want to go to therapy to change, therapy can help strengthen your own self-improvement and personal growth," said Marissa Nelson, a marriage and family therapist. The hesitant partner may become impressed by these positive changes and decide to pursue therapy after all.

If you think your own experiences with therapy have piqued your partner's curiosity, let them know that can see the therapist individually as well. "Often, by letting them know a safety zone will be created, where their voice is heard and fault or blame isn't the goal, the hesitant partner might feel safe to come in," psychotherapist Constance DelGiudice explained.

How do you know if your therapist is a good fit?

It helps to do your research before choosing a couples therapist, but the truth is that you won't really know whether they're the right for you and your partner until you get together.

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"I often arrange a phone call first with clients to make sure we are potentially a good fit," Nasserzadeh said. "Once you meet, pay attention to the therapist's communication style, the rational behind their questions and their general approach. "Any homework they assign should be explained clearly and makes sense to you and your line of logic."

How long should therapy last?

There's no one-size-fits-all answer to this question. It really depends on the couple and the issues they're working through. For some couples, a few sessions may be all they need to jump-start their relationship, while others may remain in therapy for years.

In general, it's a good idea to see a therapist together until you've met your goals and feel confident that you've gained the skills necessary to navigate the ups and downs of your relationship.