Cosmo
I have to post this because I find it funny and enlightening. Don't bother reading if you read Cosmo:
The Good:
When you fall for someone, the part of your brain that's rich in stimulant dopamine is activated, causing you to feel exhilarated. The intensity of that joy spills out into the rest of your life, mitigating any negative things that may be going on. Dopamine also cranks up production of testosterone, the hormone that rules libido, which can explain your no-holds-barred horniness and Wonder Woman-like sexual stamina.
The Bad:
While being in love can put you in the happy zone, it can also be a tad hazardous. Activity decreases in the amygdala, a part of your brain associated with fear. Your internal alarm doesn't disappear completely, but you are more likely to jump into fearful situations despite the consequences. That's why you assure your new man it's no problem (when it is) to have a leisurely breakfast rather than go to work on time.
The Ugly:
Because love sparks activity in the dopamine-rich areas of the brain associated with reward, you become as addicted to your man as you would be to a drug. When you're with him, you're high as a kite; when he's MIA, you bottom out. The more affection and atention your "love object" gives you, the more you crave--and the more depressed you'll feel if you don't get your fix. The lovesick blues may also be linked to a decrease in serotonin, a brain chemical that helps keep us calm and happy. We know that low levels of serotonin have been linked to obsessive-compulsive disorder. Some evidence suggests serotonin may drop by as much as 40 percent in people who are in love. Hence, the reason you drive by his house a million times and spend hours trying to analyze what he meant by "See you later." There's even a flip side to all that mind-blowing booty you've been having. Sex can cause your levels of oxytocin, the cuddle chemical, to skyrocket, givng you an exaggerate feeling of closeness toward your partner. It's natures way of helping you bond with your man--whether he's earned it or not.