We’ve written lots about what makes two people compatible, what eligibility means in the context of romantic relationships, and gender differences in love and attraction. 

But once a couple is established, how can we predict whether or not it’s likely to go the distance? 

We’ve broken down some of the most influential studies about exactly that. Here are four of the factors that psychologists, behavioural scientists, and sociologists have identified as playing a role in romantic longevity.

Do you believe in fate?

Some people are practical about love: realistically, we’re all likely to have a number of chances to fall in love over the courses of our lifetimes, and our romantic lives are what we make of them. Love is the result of overcoming hurdles together, growing and changing in complementary ways, and resolving conflicts. This is sometimes called a “growth belief,” because it implies that we can adapt ourselves to a variety of circumstances and turn them to our advantage.

Others are old-school romantics, taking the view that love is a question of destiny. There’s one true love for all of us out there, and finding them is the key to happiness and romantic success. And when it comes to love, we ought to follow our hearts over our heads. This is the opposite of a growth belief, because it implies that our natures are fixed, and we need to find precisely the right circumstances if we’re to flourish.

It turns out that which of these beliefs you most identify with is a pretty reliable predictor of behaviour. If we believe, for example, that our characters are immutable, we’re more likely to give up on tasks that challenge us – because, we reason, we were never going to be good at them. We’re also more likely to judge others’ characters quickly: we suppose that how they act in a given situation is probably indicative of their personality overall, rather than the result of pressures on them at the time. This leads to a greater willingness to punish other people who behave in undesirable ways. 

So which of these beliefs we adopt tends to predict both how we relate to challenge and failure, and how we judge those around us.

It also comes to bear on how we view our own romantic relationships. This makes sense: if we believe that relationships are (or should be) destined, bad signs early on are likely to make us give up. If we think relationships are never going to be perfect from the get-go, and will always require work and care to make them successful, we’ll probably place less emphasis on perfect compatibility at the beginning.

One of these outlooks brings greater benefits than the other. When it comes to love, belief in destiny is correlated with having several of the following views about relationships:

• Disagreement is destructive to a relationship
• You and your partner should be able to know each other’s thoughts and feelings without explicit communication
• You and your partner cannot change yourselves, nor your relationship
• You should be ideal sexual partners for each other
• Men and women are fundamentally different in their needs and personalities

These five beliefs are considered by psychologists to be signs of dysfunction – that is, holding them is associated with relationship instability and failure. They’re considered dysfunctional because they make it likely that in the face of relationship challenges, you’ll be inclined to disengage and give up rather than work together to maintain the relationship. 

It’s no surprise, then, that people with a strong belief in romantic destiny see effects on their romantic relationships. In general, the relationships of people who believe in destiny are likely to be shorter. Partners are less likely to stay friends afterwards, and more likely to write off the whole relationship as having been wrong from the beginning.

There’s one exception to this: if you’re a believer in fate and you meet someone who ticks all your boxes (or, in the scientific literature, someone with whom you experience a particularly satisfying and close relationship) straight away, your relationship stands a good chance of lasting unusually long. So all is not lost: you might just have to spend a little longer kissing frogs before your true love comes along.

Can you lie to yourself convincingly? 

Most of us like to think we’re fairly honest with ourselves, and realistic in our appraisals of those around us. 

But realism can sometimes be the death knell for romance. Creating and sustaining positive illusions about our partners actually predicts higher levels of relationship satisfaction, as well as higher levels of love and trust – along with lower rates of relationship conflict and ambivalence, in both dating and marriage. And the stronger these illusions are, the more likely our relationships are to last.

In many ways, this makes sense: when more than 40% of marriages end in divorce, believing that our own relationship is no better than the average is unlikely to lead us to marital bliss.

Healthy relationships require a leap of faith. But to make this, we must have confidence that our romantic partner is almost without fault: we must believe that their eye never wanders, their affections never tire, and that they never think badly of us. We can’t read our partners’ minds, and so to hold those beliefs with genuine confidence, we have to allow ourselves a little illusion.

And it turns out that this illusion can be very powerful. In healthy relationships, we project our ideal partner’s traits onto our real partner, seeing their actions in the best possible light and believing the very best of them. Positive illusions are positive projections for the future, and the two work together to create a virtuous circle: we choose to anticipate happy outcomes, which encourages us to work towards them, which makes them more likely.

These goals can also act as buffers in times of stress. Instead of pulling and worrying at the problem, beginning to shred the fabric of our relationships, we can point to goals and visions that we have in common with our partner. We can find cause for optimism, which gives us a greater sense of control over our romantic future, which in turn creates relationship stability. 

It’s no surprise, then, that when both people in a couple idealise each other significantly, the relationship is more likely to last. In fact, the existence of these shared illusions seems to be a better predictor of relationship stability than actual relationship satisfaction – because over time, reality begins to converge upon the illusion, creating the ideal relationship for both partners.

Do you know yourself?

People in relationships are better at predicting their partners’ behaviour when their partners know themselves well. This is referred to in behavioural literature as “high self-concept clarity,” which is just another way of saying that we have a good measure of ourselves as individuals. We know what we do and don’t like, we know how we’re likely to react in any given scenario, and we know what kind of people we like to be around.

How well we know ourselves is closely related to how well other people can predict our behaviour. So the better our self-knowledge, the easier it is for those around us to interact with us. Giving someone news when you don’t know how they’ll react can be intimidating; being in a relationship with someone unpredictable and inconsistent can be exhausting.

There’s another factor, too: when we know ourselves and our partner very well, something called the Michelangelo phenomenon can occur. As we’ve seen above, in constructive relationships we view our partner as their ideal self. This makes us attend closely to their best characteristics, and generally act in ways that elicit the best from them – making our partner become more like the ideal version of themselves over time. 

It also helps that if we know how we’re going to act in the future, we can prepare ourselves. This has lots of useful applications for handling conflict and external sources of stress, both of which can pose threats to relationships if not managed well. 

People who don’t know themselves well tend to miss out on essential relationship-building activities. Intimacy means learning to let someone become part of ourselves, but if we already have a vulnerable sense of self then we’re often less willing to do this. Refusing to expand our sense of self means we can’t grow and evolve together with another person, which in turn prevents us from developing enduring relationships.

Not knowing ourselves well also tends to mean we’re worse at choosing partners. We have a fuzzier sense of what kind of person would suit us, or even what kind of person is similar to us, meaning our romantic selections will be less well-informed and so potentially less suitable in the long term.

Do you like yourself?

Self-esteem is a strong and reliable predictor of relationship satisfaction. If we like ourselves, we’re more likely to be in relationships that make us happy. There are lots of reasons for this: we’re less likely to act in self-destructive ways (e.g. by choosing a partner who is actively cruel or unpleasant to be around), we’re more likely to have faith in our ability to resolve problems – which, as we’ve seen, actually makes us better at resolving them – and we’re more likely to have a healthy well of optimism from which to draw in times of difficulty.

But it isn’t just relationship satisfaction that self-esteem can predict. This article focuses on relationship stability and longevity, and it turns out that self-esteem is a useful predictor of these traits too. We’re more willing to persist in relationships that we trust ourselves to manage, and we’re more likely to trust ourselves to manage relationships if we believe in our own ability to manage situations in general. 

Without strong “can do” beliefs and behaviours, we’re easily overwhelmed by setbacks and negative feedback. In fact, negative feedback can be particularly destructive to both our sense of self and our self-esteem unless we have a positive narrative about ourselves that we can fall back on. Just as it can be beneficial to project ideal qualities onto our partners, it can be beneficial to have high (even unwarrantedly high) confidence in ourselves and our own decision-making skills.

Faith in our own ability to resolve conflicts is closely related to less romantic relationship conflict overall, but also greater persistence in solving problems that do arise. Even more tellingly, self-confidence in this arena is related to greater levels of trust in our partner: we’re more likely to believe that our partner is trying their best and will end up doing the right thing – a belief that’s essential to relationship stability – if that’s true of ourselves, too.