I've been to a decent amount of weddings, so I've heard all the stuff about perfect couples who stick together through thick and thin, supporting each other when the going gets rough.

So far though, the most poetic description of sustainable love that I've ever heard came from Alexandra Solomon, a psychologist at Northwestern University.

“Two people who are able to competently handle all of the sh— that hits the fan,” she told me. “That's the biggest thing a long-term relationship needs in order to be successful.”

Solomon teaches a course at Northwestern called “Marriage 101”; she recently published a book titled Loving Bravely. In the book, Solomon guides readers on a journey toward relational self-awareness, which she defines as “the ability to take a curious stance vis a vis yourself.”

In a recent article on PsychologyToday.com, Solomon flipped that concept on its head and showed readers how to look for a partner who is also relationally self-aware.

I spoke with Solomon about why it's important to find a relationally self-aware partner and she told me that “external trappings” — think jobs, income, appearance — tend to “come and go.”

She went on:

“When I get laid off or when you get transferred, you want somebody who has the tools that it takes to sit in all of that complexity of: How do we value your job needs versus my job needs? What comes up in me when you tell me that you want to move us across the country? How do we work shoulder-to-shoulder, side-by-side on that kind of stuff?

“That to me is far more important than the job description somebody has.”

It's not so easy to gauge someone's relational self-awareness level on the first few dates. But if you notice that the person blows up at the waiter for bringing them the wrong drink, or screams at another driver who cut them off, that's not a great sign.

In the Psychology Today article, Solomon also suggests paying attention to how the person talks about their past relationships. She writes: “People who don't have much relational self-awareness tell stories (especially love stories) that are full of blame and shame. They tend to cast themselves as victims and other people as suckers, losers, or fools.”

On the other hand, a relationally self-aware person might say something like, “It wasn't the right time for us,” or “It was painful, but I learned from the experience.” As Solomon puts it, they can appreciate the “shades of gray.”

Once you're in a relationship, notice how the person handles themselves during conflicts.

Solomon told me: “Without relational self-awareness, what happens is I slip into into blame — I see it as your fault because I'm blind to my own role in it — or I slip into shame — because I'm not paying attention to your role and I'm convinced that I'm the problem and I ruined the whole thing.”

A relationally self-aware partner will realise that you both messed up and “ended up way down this rabbit hole of misunderstanding.”

Ultimately, Solomon told me it's pretty useless to try to “get” your partner to become more relationally self-aware. A better bet is to try working on your own relational self-awareness and act as a role model for them.