Jealousy=lack of self-confidence?
It is common for people to believe that the only reason for jealousy is lack of self-confidence. They explain jealousy with the fact that a person who is jealous is a person who feels that he or she is not good enough. People believe that a problem is in the one who is jealous but not in the one who is being jealoused. Though, it is worth to think about the fact that any conflict takes two. It is impossible for one to get mad about nothing. There should be a reason for it and there is a reason for it. And whether the reason is true or false it is a question of different nature.
The main thing that it is wrong to consider that there is only one guilty person. In no case jealousy may be recognised as the lack of self confidence. It is the most common and wrong way to explain this feeling. If you'll take a good look on statistic or simply on the world around you you'll notice a number of successful people who always mad about their jealousy and suspicions that occupy their minds. So, no, jealousy is not equal to lack of self-confidence. Jealousy is equal to inability to trust people.
Those who are jealousy passionately believe that there is no one to be trusted. They always afraid of betray and the pain that will come with this betray. They don't believe even to themselves and so it is not hard to be that they can't trust to another person. This disbelieve may be resulted with a number of different factors. But the main characteristic of the factors is a pain a person underwent. It is possible that a jealouser had a negative experience. It is possible that he or she trusted someone they were in love with and they would never believe that "someone" can betray them. Though, obviously "someone" appeared to be rather skilful at it.
So, this pain, they underwent and betray they considered to be impossible, resulted in disbelieve. It doesn't mean that such person considers you to be a betrayer; it means that such person considers everyone to be prospective betrayers. Sure, you may say that it is his or her personal tragedy and you are not obliged to suffer from this. And you will be right, no one can make to endure it and no one may say that it is your duty. It is your own choice whether to deal with this problem or to walk away.
In case if your choice is to deal with it you have to realise that the problem has nothing to do with lack of self-confidence and so words like "You are the best" or "There is no one like you" will never help you to deal with the problem. But, the effort applied in order to make him or her trust you will. You have to do your best in order to prove the person that there is nothing to be worried about and that you will never betray him or her. Once you managed to fulfil it the problem of jealousy will never disturb you again.