A couples therapist shares 5 signs you'll have a strong marriage

• While it's impossible to predict how long a marriage will last, there are some signs to look out for.
• A couples therapist shared some of the most important qualities of a healthy, happy relationship.

Before you marry a partner, you should make sure your relationship is solid.

While it's hard to predict if a marriage will last, Avigail Lev, a San Francisco therapist who treats couples, said there are a few habits you should adopt — and signs to look out for — if you want a lengthy, loving partnership.

You both 'accept influence' from each other

John and Julie Gottman, famed relationship psychologists who are also married to each other, researched the most important elements of healthy marriages for decades.

In one long-term study on newlyweds, the ability to "accept influence" from a partner predicted happier marriages.

"It's the idea that your partner is impacted by your thoughts and feelings," Lev told Business Insider. You don't feel the need to be passive-aggressive or threaten to leave for them to make adjustments for you. Instead, they pay attention to what you say, take your emotions seriously, and are actively interested in finding solutions with you.

Lev said that healthy relationships need both people to be "willing participants" ready to communicate, listen to each other, and change in ways that make both parties happy. Otherwise, you stay stuck in conflict or cycles of punishing each other, eroding trust.

You know your values — and align with them

One of the biggest reasons people feel unsure about their relationships is that they don't know themselves, Lev said. They might not know if their criticisms of their partner are too unreasonable or if they're mismatched.

She tells clients to do a simple exercise: track your values.

To start, you write down your 10 most important values, like honesty, cooperation, or a sense of humor. Next, put a number next to each of those values, ranking their importance. "If everything is a 10, you're not going to get that in a partner," Lev said.

For the next three months, consistently score yourself and your partner on each value. Do you want affection from your partner but not give it back? Do you crave adventurousness but never suggest ideas for dates? This exercise will expose the gaps.

"I've never seen a partner be able to end a relationship when they themselves score low on their own values," Lev said. If you can't live up to your own standards, it's impossible to tell if your standards are too high.

If your partner accepts influence, they'll often start to mirror your positive changes. If you score high on collaboration and accountability but your partner stays the same, "there's your answer" that you're in the wrong relationship, Lev said.

You have your own lives

Another important quality is interdependence. It's not only about having your own hobbies and friends but also about having your own beliefs and emotions.

"Couples often start sharing a mind, almost," Lev said. "When people get too enmeshed and codependent, it actually harms the relationship in many ways. It breaks down passion and excitement and respect."

If you expect that you think and feel about everything the same way, you may start making assumptions that you already know what the other person is thinking. But in a healthy relationship, "you don't expect your partner to be psychic and know all of your needs," Lev said.

You know when to take breaks

One of the most effective things Lev sees successful couples do is take time-outs during heated conflicts.

"A lot of couples don't understand that once you're triggered, you're no longer in your prefrontal cortex," Lev said. "You're in your primitive amygdala brain. You're not coherent, and you need to stop."

Couples who recognize when they're emotionally dysregulated and can take a 30-minute break are usually much more productive in their arguments — and avoid saying things that linger long past a squabble over dishes.

Otherwise, Lev said, they end up trying to regulate each other's emotions instead of talking through their needs.

The better option is to wait until you're calm and explain how a specific behavior, like sporadic texting, makes you feel.

You express gratitude

Another Gottman rule that Lev loves is the "magic relationship ratio" of having five positive interactions for every negative one.

"For every criticism, you should give five compliments," she said. Expressing gratitude for your partner, hugging them, or appreciating a small change they made are all ways to keep your marriage optimistic and light.

It doesn't mean you should opt for toxic positivity in your relationship. "We don't have to decrease criticisms," she said. "We just add more appreciation and gratitude."