Robert Pattinson and Kristen Stewart
Actors Robert Pattinson (L) and Kristen Stewart arrive for the British premiere of 'The Twilight Saga: Breaking Dawn' at Westfield Stratford City cinemas in east London November 16, 2011. REUTERS/TOBY MELVILLE

After a year of the Twilight couple's heart-breaking split, Robert Pattinson opened up about the break up. The couple broke up due to Kristen Stewart's infidelity, from 2012 to 2013 they were on an "on and off" relationship; finally separating in May 2013.

In an interview with Esquire magazine, he spoke of his break up with Kristen. He said, "S**t happens, you know? And honestly, who gives a s**t?"

Kristen was having an affair with director Rupert Sanders, 43. This shook their relationship and led to a break up, which was hard on both of them; Rob, however, was at the receiving end both times.

Rob explained that his break up was not easy, and he went through a tough phase. "The hardest part was talking about it afterwards. Because when you talk about other people, it affects them in ways you can't predict." He described, taking reference from a scene in Doubt with the late Philip Seymour Hoffman. In the scene, he said, "Where he's talking about how to take back gossip? They throw all those feathers from a pillow into the sky and you've got to go and collect all the feathers."

He also admitted that he was finding it difficult to date other women. Rob took to gymming, quitting cigarettes and dating other women for short periods to get over his break up. While the young actor had taken to these methods to overcome his break up, other people do other things, some have rebound sex and some weep for a long period and come out stronger.

It is not surprising that Rob found it hard to get over Kristen; according to a survey conducted in the United States, approximately 81 per cent of the people said they still think excessively about their former lovers though they are not together. A lot of men and women are unable to move on, and there are scientific reasons to explain their inability to move on.

No one can accept rejection easily

People find it hard to deal with rejection. Scientists from the University of Amsterdam conducted a study and found that rejection is related to significant response of the parasympathetic nervous system. The parasympathetic nervous system takes care of the body when at rest. Research found that it gives a feeling that you are not liked," so one reacts emotionally and physically. Rejection caused a reduction in heart rates as well.

Relationships become an addiction

A study by the Stony Brook University revealed that the parts of the brain that cause pain and anguish and are active in drug addicts were the same parts that got active in people who had just experienced a break up. Brain imaging showed similarities between romantic rejection and cocaine craving, so it is natural to experience withdrawal symptoms as well.

Does not matter who ditches whom, loss is difficult to handle

A study showed that the pain of losing a relationship is more than the joy of starting a new one. Psychologist Daniel Kahneman received the Nobel Prize for his work in Prospect Theory that describes how people choose in situations that demand a decision between alternatives that involve risk. It found that the brain views loss as more important than gain. Since loss is seen as a risk, the person who experiences the loss tends to avoid future relationships which are seen as a risk.

The past never lets go

The past is difficult to let go and people tend to look at the future through a mesh of the incidents that have occurred in the past. But overcoming failures gives way to success and makes one feel more accomplished, so one must try overcoming the problems.

A series of failed relationships makes you believe that there never will be a successful one

The problem here lies with the perception of life and not life itself. Psychologist Jessica Witt at Purdue University conducted a study on football players. She found that their success and failure to score a goal determined their perception of the field post. Series of failures made them view the field post as taller as and narrower than what it really was, and success made them perceive it as larger than before. So, the more rejection one faces, the more likely he is to perceive relationships and himself in a bad light.