Oxytocin is a hormone that facilitates pair bonding and mother-infant bonding by stimulating feelings of love and trust. It is secreted during and after sex (in both men and women), during childbirth, during experiences of social intimacy and connection, and from physical touch such as hugs and massage.
Here is some of the interesting stuff I found:
Exposure to cuteness, such as pictures of kittens, can trigger an oxytocin rush.
The presence of oxytocin relieves anxiety, reduces stress, and may be an effective treatment for PTSD. It may also lead to longer life.
Taking care of yourself, by journaling and nesting, can help maintain healthy oxytocin levels.
Oxytocin is not all lovey dovey - it can increase feelings of envy and schadenfreude, as well as the desire to betray others. Creepy.
Oxytocin's effects are more pronounced in women, because testosterone tends to mute its effects, but guys need hugs too.
An "in love" feeling can also be due to dopamine and norepinephrine, not just oxytocin. One psychologist recommends that women date 3 men at a time to avoid becoming accidentally bonded to someone she doesn't know well enough.
Pets may experience genuine feelings of love for their owners - meaning that when they act devoted, they aren't just manipulating their sources of food.
Oxytocin supplementation seems dicey, but it looks like acupuncture may work. (Of course, there are a lot of "natural" ways to stimulate oxytocin, from sex and cuddling to caring for a sick person to practicing generosity and gratitude.)