Researchers at the University of Wisconsin-Madison Medical School* have discovered that using Viagra can boost sensations of love, driven by hormone oxytocin. Physiology professor Meyer Jackson suggests that Viagra might be used to promote "social-bonding".
While experiencing social bonding, though, you might have side effects such as erections, which may last more than 4 hours, in which case you should seek medical attention. Which could interfere with your social bonding.
* Disclosure: I worked for the Medical School, and graduated from UW-Madison.