The 3 Things Every Relationship Needs to Last, According to a Psychologist - VICE

There are a million ways to overthink a relationship. Attachment styles. Love languages. Compatibility quizzes. A late-night Reddit search after one out-of-pocket text.

One theory has been around since 1986 and is still getting research support. Psychologist Robert Sternberg’s Triangular Theory of Love says romantic relationships are made up of three things: intimacy, passion, and commitment.

A 2026 scoping review reviewed 27 studies on Sternberg’s theory to see how well it still held up nearly 40 years later. The answer was better than you might expect. Researchers found the same three pieces kept showing up across different cultures and relationship types.

Here’s what each side of the triangle actually looks like in real life.

Intimacy is when someone actually and truly knows you. Not just your coffee order, but how you act when you’re stressed, what you’re insecure about, and what kind of support you need without having to spell it out every time.

Sternberg describes intimacy as closeness, trust, and connectedness. In real life, that can look like making the doctor’s appointment, bringing home dinner after a brutal week, or remembering the thing your partner mentioned months ago. “Each person’s ideal is different,” Sternberg told Cosmopolitan. “There is no one ideal that works for everyone.”

Passion is the obvious one, and probably the one people panic about first. It includes sexual attraction, but Sternberg’s version is broader than sex. It’s the pull toward someone, the feeling that being connected to them still has some charge.

That charge usually changes over time. Research on long-term relationships has found that passion commonly peaks earlier and softens later. That doesn’t automatically mean something is wrong. The better question is whether it’s still there in some form and if both people care about keeping it alive.

Commitment is the unexciting one until the relationship goes through a rough patch. Sternberg describes it as deciding you love someone and continuing to choose the relationship as life changes around you.

That becomes especially important when intimacy or passion is feeling a little…blah. Long relationships have boring stretches, stressful stretches, and periods when one person carries more than the other. Commitment is what helps keep the relationship together while the other pieces find their way back.

Sternberg’s model also allows the triangle to change. Long-term relationships usually lean harder on intimacy and commitment than they did at the beginning. That’s normal. What matters is whether or not both people still want the same relationship. If one person wants closeness and stability while the other chases intensity, that mismatch will show up somewhere.