The green-eyed monster.

Jealousy! of course, what else. I found a few interesting quotes on jealousy over the net:

"Love sees sharply, hatred sees even more sharp, but Jealousy sees the sharpest for it is love and hate at the same time"

"Jealousy is that pain which a man feels from the apprehension that he is not equally beloved by the person whom he entirely loves"

"The jealous are troublesome to others, but a torment to themselves"

"There is never jealousy where there is not strong regard"

"To jealousy, nothing is more frightful than laughter"

"Jealousy is the greatest of all evils, and the one which arouses the least pity in the person who causes it"

There are so many reasons why people get jealous... especially when it comes to their partner. It could boil down to abuse when he/she was a child, or perhaps their partners have cheated on them over and over again in the past. Whatever the cause and reason, jealousy is seen as a defence mechanism to protect oneself from getting hurt. But of course, in turn, it hurts the other person too in the process.

Jealousy - as bad as it can be, can actually be involuntary. It can't be helped, it just happens. It's like a bad habit no one can kick. The ones who get jealous are aware of this destructive problem, and yet are powerless to control it. Their insecurities took control. Those who have tried to hide it, end up hurting themselves eventually because the problem was never resolved.

These people are also afraid to ask protruding questions that have been clouding their minds, because their partners suddenly become angry and defensive... It then becomes a cycle. They need comfort, but the partners felt attacked.

The only key to this problem is communication. The jealous one needs to know that there is nothing to worry about. And the partner needs to be patient when asked these questions for comfort.

There is no room for jealousy when he/she feels loved.