Love can change the world, but it can also change your brain. A recent study compared brain activity across people in various states of love (or lack of it). Here are some of the results:
Here, LG is the love group, SG is the single (and never fallen in love) group, and ELG is the ended-love group—the poor folks who had recently broken up with someone they loved.
The most important message here is that there are differences between the groups. And this is not the result of doing an activity that activated their brains; these people were just chilling out in an fMRI machine, not thinking of anything in particular. In other words, the way your brain functions changes when you fall in love, and not just when you're with or thinking about your sweetheart. Your brain changes again if that love comes to an end—but doesn't go back to the way it was before you ever fell in love.
It's a spectacular confirmation of what many of us probably would have guessed, based on how subjectively intense love can be. But if you're lucky enough to be in the LG, maybe avoid turning to science for love notes. I even tried putting a quote from the paper on a romantic meme, but it still doesn't quite look right: