There are a few stories out there that caught my attention. The first one involves the size of the tail in male fish: "female green swordtail fish mature more rapidly if they spot a male with a big tail. Likewise young males retard their sexual development for several months if they spot a better-endowed male". You're free to make your own conclusions on that one. The second story shows a link between vasectomy and dementia, I bet you didn't see that one coming. Finally a third story shows that nagging does not work since even when shown the name of the significant other subliminally, you are less likely to perform a task. From the article "The main finding of this research is that people with a tendency toward reactance may nonconsciously and quite unintentionally act in a counterproductive manner simply because they are trying to resist someone else's encroachment on their freedom.".
But My favorite is this article on which region of the brain is reponsible for the feeling of love itself. I love it when scientists talk dirty like that: "Dr. Brown said scientists believe that when you fall in love, the ventral tegmental floods the caudate with dopamine. The caudate then sends signals for more dopamine. The more dopamine you get, the more of a high you feel [...] Lots of dopamine, in turn, triggers the production of testosterone, which is responsible for the sex drive in both men and women." . One of the experiments in question that made people cry in an MRI machine reminds me of Dr. House :"Now their research is centered on the flip side of love. They've recruited college students who'd just been rejected by their sweethearts. Again, the scientists performed MRI's while these students looked at photos of the objects of their affection."