This is something inspired by a friend of mine, impishlaugh. Apparently, when you break up with someone, even under the best of circumstances, you can feel the pang of loss and regret that they're not around anymore despite your best efforts to feel good about it. Some people call it "the blues" and others just call it heartbreak. No matter who you are or what you do or how you do it, this is almost entirely unavoidable. Symptoms may include:

Depression
Anxiety
Irritation
Binge-eating
Snapping at friends
Issuance of death threats
Confusion
Stress

Not all these symptoms apply in every case. The best known remedy for this condition is simply giving one's self time to adjust to the change. Acceptance and forebearance are good remedies, as well. Communication and being realistic about your options are almost a necessity, akin to taking Vitamin C when you have a cold.