Almost everyone has that ex they stayed with for too long, that one who never listened, treated them horribly, or could never commit, but still held an inexplicable power and magnetism. But whose fault was that?

You might try to blame yourself for relationships with completely unsuitable people, but it’s not that simple. As it turns out, biology might be as much to blame for any misguided choice in partners. Cue a loud, prolonged sigh of relief.

That’s not to say that we don’t and can’t have agency over who we date. It’s just that the burning in our loins can lead to somewhat ill-thought-out decisions as we navigate the world of dating.

We broke up with the myths and embraced science to try and clear up why you dated that complete buttmunch (and nobody likes one of those) for so long.

The science on this is highly subjective — there’s no measurable benchmark for “attractive” just as there is no scale to confirm beyond doubt how “lit” something is. It’s also based solely on heterosexual couples — an approach that simply doesn’t scan in 2020.

Some people don’t even look for sexual relationships at all, and there is a decline in sexual frequency among millennials.

Let’s look at the studies anyway, because it’s important to examine all sides.

In a small-scale study, men and women looking for short-term sexual partners placed physical attraction high on their list of desirable qualities.van Straaten I, et al. (2008). Sex differences in short-term mate preferences and behavioral mimicry: A semi-naturalistic experiment. So it may be as simple as looking for a brief fling with a someone you think is hot and not caring too much about what they’re like on the inside.

However, don’t entirely count out the power of biology in these decisions: Another study suggests that hormones play a key role in choosing a romantic partner even after the awkward adolescent years.

In this one, women who were ovulating (meaning they were at their peak fertility) checked out fake online dating profiles of different men. They were much more likely to pick confident studs over guys they deemed average-looking than women who were not ovulating.Durante KM, et al. (2012). Ovulation leads women to perceive sexy cads as good dads.

Women even chose the people they perceived as hot if they were designed by the study authors to seem unreliable, financially unstable, or commitment-phobic.

Another series of three studies found that there’s a subtle two-way conversation during a woman’s peak fertility period that occurs without words.Miller SL, et al. (2011). Ovulation as a male mating prime: subtle signs of women’s fertility influence men’s mating cognition and behavior. The study puts this down to the evolutionary theories on the fertility window — men not only pick up on pheromones more keenly during this time, but also mimic the less selective behavior of women during these few days.

In a world where sex is about pleasure and personal independence as well as reproduction, it’s now less about making babies and more about the residual feelings of sexual pleasure that evolution has left us with.

On some level, we end up with unsuitable partners because those horny stirrings mean we’ve got short-term bump ‘n’ grind on the brain, rather than a ride off into the sunset.

But we’re also not idiots, and know full well that the quickie at a house party may well not become our eternally betrothed. We also know not to take a few tiny studies at face value.

One of our writers went on 300 Tinder dates to help you with the world of short-term romance. Perhaps you could learn a thing or two from their adventuring.

These studies also have pretty severe limitations. They focus on heterosexual couples and don’t explain why many LGBTQ+ people also end up with deeply unsuitable people who hurt them.

In fact, a different study took place, involving 439 homosexual men and 365 heterosexual men.Gobrogge KL, et al. (2007). Homosexual mating preferences from an evolutionary perspective: Sexual selection theory revisited. The researchers found that a person’s preference for long-term partners also depends on factors outside of evolutionary urges to procreate.

So science doesn’t hold all the answers. Relationships are a learning curve. We don’t always know what we like and sometimes fail to appreciate the people who really appreciate us.

The above studies don’t account for changing tastes over time. You may well not want the same things at 20 years of age that you do at 30, 40, or 50 years.

While, yes, we may get a flutter in the belly when we see a person who registers to us as attractive, it may not be until later on that we realize they’re not all they seemed to be in the first few months. People regularly present a false account of themselves during that honeymoon period.

Also, the “physically attractive” mentioned in these studies is not the same as attractive. Confidence, ambition, humor, intelligence, and just about any quality under the sun can qualify as attractive based on your personal taste.

Sometimes, we date people who actively behave like assholes, quite simply, because we’re still working out what to look for. People might hang on to relationships through insecurity or being worried about the emotional intensity of a break-up. We might give people the benefit of the doubt more than they deserve.

And, if you’ve ever spoken to people on either side of a break-up, they will almost always think the other person is the asshole. People are sometimes incompatible. They also change.

It doesn’t make you stupid or naïve. It makes you a human being who sometimes makes decisions based on wants, not needs. Or a human being whose needs change over time.

It’s also the case that some people remain in toxic relationships far longer than is healthy due to changing circumstances. Maybe they have a child with their partner and fear the consequences of a split. It could be that one partner has become financially or emotionally dependent on the other.

Perhaps they fear the hefty expense of divorce (on average, in the United States, it costs around $15,000 per person).

It isn’t always as easy as walking away.

So it’s important to be selective and know your self-worth in the early stages of a relationship. This can help you make sure you have a truly nourishing, long-term connection once you reach a stage where leaving isn’t so easy.

While “jerks” might be good for a few dates or even the occasional tryst, research suggests they don’t typically make the cut as spouses. Some researchers have noted that men and women look for other attributes in a long-term partner besides physical attractiveness.

According to the study, both sexes typically seek kindness and intelligence when they’re in it for the long haul.Miner EJ, et al. (2010). Mate attraction, retention and expulsion. (These findings are relevant for people of all orientations and identities. Kindness and emotional intelligence are pretty universally wonderful.)

A conflict-free life would be ideal, but it’s through the less endearing people we date that we can set values and benchmarks below which we don’t allow ourselves to dip in future. And hindsight is an excellent life coach.

(Here’s how to work out when you’re making the wrong decisions.)

While there’s no one-size-fits-all approach to ending up with the “right” person, there are a few measures you can take to dramatically reduce the risk of being with someone you don’t like.

  • Learn to love yourself. Ru Paul is correct — how in the hell you gonna love someone if you don’t love yourself. Working on your self-esteem is the best possible way to make sure you’re making decisions that work for you.
  • Qualify others by your own values. Dating is not an audition process, and having someone gorgeous sitting opposite you doesn’t mean they’re “out of your league.” If you’re looking for long-term love, you have to make sure your other half is a long-term investment. They should prove themselves to you — not the other way around.
  • Communicate. Your partner is not going to be the same person on your first date as they are 10 years down the line. It’s important to check in with each other regularly and make sure you’re on the same page.
  • Remember to have fun. Not every person you kiss or sleep with is The One — in fact, there’s no such thing, and that’s great. Explore your own tastes and preferences, don’t make commitments you aren’t 100 percent behind, and be sure to set the expectations of anyone you get involved with.

There’s no science to getting relationships right, but there is an art to it. It won’t be speedbump-free, ever. But you can avoid spending too much energy on relationships with people who aren’t on your team by having standards for yourself and knowing you’re worth enough to stick to them.

No single study can cover all ground when it comes to relationships.

Yes, we no doubt have some evolutionary habits that drive our sexual urges and decisions. But evolution also helped us develop a sense of ourselves and the ability to pick long-term partners who are great for us.

Sometimes, we simply don’t get it right. And that’s fine. But learning from our mistakes is the most important part of finding a reliable, loving, kind partner who wants what’s best for us.

And just because a relationship is getting a little stale, it doesn’t automatically mean you’re with the wrong person. You might just need to add a bit of pep — we came up with 19 places to start refreshing your connection.