Recently, the Prince Harry announced his engagement with an American actress. When the media asked him when he decided this girl would be his lifetime partner, he said the moment when he saw her for the first time. Love at first sight sounds romantic and many young people believe that the first feeling about another person is really important, because it always decides whether they can be couples in the following days. While many old people think love at first sight doesn't exist, because they need to know the personality, which will decide the charm of another person. For a relationship, the good first impression can bring passion and love, but it can't maintain the relationship for lifetime. The way to get along with each other and the tolerance of both sides are key factors to decide whether a couple can stay forever.