I don't remember where I read this or heard this. For a very long time I thought maybe Barney in How I Met Your Mother would've said this but only later, when I wanted to reread the theory so I Googled and found out there was no Olive Theory in Barney's book. Anyway, the theory is pretty true and a lot of people know about it too. Maybe the name of the theory would've been something else. But this is how I've remembered.
In magnets, like poles repel like poles and opposite poles attract each other right? Also, its impossible for the two poles to exist individually. Fun fact : Scientists are working on creating monopoles but they haven't been successful yet.
So yeah, the same attraction and repulsion exists in humans too. When two people completely unlike each other meet, initially they usually feel awkward. If they do further interact, they start finding some interest in each other. This is because when opposite people meet, they get to understand different point of views. Now THAT is what makes life interesting, isn't it? Looking at life in a way that you wouldn't have ever before? Every time one person says something about a theme, the other will learn something entirely new and when the other shares their point of view, the former learns something new. The two will always wanna learn more about the other.
The olive theory is a theory to find you your perfect partner. According to the olive theory, if you think someone is too much like you, you'll probably end up fighting with each other. Find someone who is somewhat opposite to you. Such relationships last long.
I didn't and still don't believe in this theory completely. I mean... Its not necessary for two opposite people to always be interested in each other, like, come on. I'd be interested in someone who's completely like me, too. They'd understand everything I mean perfectly. When I told my friend this (who btw completely believes in this theory), he said, "If you meet someone who's like you, you'll eventually get bored. If you're bored, you'd start avoiding each other and then come an end to whatever there was in between you two". Well. I know quite a few people who aren't like me and are lethally boring. Also, if you meet someone who's completely unlike you, there will be a point when you'll just want them to listen to you and understand things the way you look at it. You'll get sick of it. Saying something and always listening to someone else say "No, I don't think so" is already a nightmare.
I'd say The Olive Theory might be right to some extent but after that if you want to have a perfect relationship with anyone, there has to be love. Love in between friends, love in between lovers. Hell, love even exists in between nemesis. Would you be able to live without your nemesis? If you think about it, you always have one and if you think you don't, think deeper because a life without an arch-enemy is like a day without (rain? No! Eww.) oxygen. Haha.