Researchers have found that, at least at first, it’s hard to tell the difference between a long-term and short-term relationship. And there's an obvious culprit.
In the study, published in the Journal of Experimental Psychology: General, the team from the University of California, Davis, surveyed more than 800 people over a range of ages. They used a “relationship reconstruction” survey to get the participants to reproduce moments in prior relationships, right back to the beginning.
What they found was that in both long-term and short-term relationships, romantic interest rose at a similar rate. That means at the start, the participants had similar experiences regardless of how long the relationship lasted. So they all enjoyed the good times at first sight, so to speak. "Short" was used to refer to experiences like a fling or a one-night stand, whereas "long" was a long-term committed relationship.
But there came a point where it plateaued and declined in short-term relationships, while in long-term relationships the romantic interest continued to climb. This suggests that despite those initial feelings, you might not know exactly where the relationship is going to go.
"These initial impressions did not strongly predict how long the relationship would ultimately last," Dr Paul Eastwick from the University of California, Davis, lead author on the study, told IFLScience. "Generally speaking, romantic compatibility is very hard to assess until some time has passed."
The team noted that some of the most interesting moments in the relationships happened before anything sexual had happened, with people wondering if the relationship would go anywhere or if they were really into the other person. But at a certain point, they start to diverge, with some relationships collapsing and others continuing.
So what causes the split? Well, the prime suspect looks like it’s that old classic: sex. According to the study, if people hooked up and thought it was pretty good, they’d try and turn that experience into a relationship. Those that were “meh” didn’t last very long.
If people were "just a little" attracted to the other person, then they would keep having intimate relations, but not for long. Long-term relationships, on the other hand, tended to be "especially exciting and sexy". Their words, not mine.
"In many cases, the first sexual experience is a marker for whether people want to try to keep the relationship going or are content to let it peter out and/or become a very casual thing," Dr Eastwick said.