There is no problem when you are happily in love with the right person. The problems occur when you are rejected in love. Stalking, Depression, Suicide, Homicide can be the side effects.
Why heartbreaks heart so much ?
Romantic love has a constellation of personality trace of characteristics. Then among them there is one trace called separation anxiety , which is well known in this cases. When you are separated from the person you will get angry , you want them to text , you want them to write , You want them to call, You want to tell them "I love you ". The researchers says that when we get rejected, the brain region linked with profound addiction will activated. Also the brain region linked with feelings of attraction , romantic love and attachment become active. The brain region which links to the psychical pain also get activated this time.
In summary it's a bad deal , You still madly love with the person, deeply attached to the person , craving the person , obsessively thinking about the person , the person has become an addiction for you and you are in physical and emotional pain.