Love can be a very fickle feeling.
One moment you think you've found the love of your life, and then the next you've realized there's no way you'd want to spend the rest of eternity with them.
While love can be a an intricate, awe-empowering emotion, so can be the realization you no longer feel the same way about your partner.
According to an article written by Romeo Vitelli for Psychology Today, evolutionary psychologists have long argued that the ability to end a relationship and prepare for a new one can have definite advantages in terms of improving the ability to reproduce successfully. He said while it's common for some species to mate for life, humans generally don't.
Brian Boutwell, the associate professor of criminology and criminal justice, and epidemiology at Saint Louis University, published an article in the Review of General Psychology that suggests humans have subconsciously formed a mental mechanism - called primary mate ejection - to sever the emotional bond between romantic partners.
Boutwell's research has found opposing factors on why men and women choose to activate their primary mate ejection modules.
1. Why men end a relationship
Boutwell said a major deciding factor for men to end a relationship is based on if his partner has had a sexual relationship with another man. He reports from an evolutionary standpoint that men are intrinsically wired to avoid "raising children that aren’t genetically their own."
"Men are particularly sensitive to sexual infidelity between their partner and someone else," Boutwell said. "That's not to say women don't get jealous - they certainly do - but it's especially acute for men regarding sexual infidelity."
2. Why women end a relationship
In contrast, Boutwell said a woman is typically more inclined to break up with her partner if they engage in an emotional affair. If they are unfaithful in that regard, natural selection subconsciously allows women to end their relationship in order to pursue a mate who is willing to provide them with a plethora of resources. This can range from helping to raise a child to providing physical protection.
However, Susan Orenstein, a licensed psychologist and relationship expert in Cary, North Carolina has said there isn't just one underlying factor that causes you to fall out of love.