There are always people that are gonna be jealous.
they are just miserable people whom want others to have a pathetic and/or troubled life like them. They may not have experienced happiness and are jealous of the life others have, constantly a bore to others.
How would being happy for someone else effect their lives? They might just feel nothing.
I don't know
I guess it's a lack of feeling secure within themselves?
They feel jealous that someone may have something that they don't or can't have?
it because some people are so jelluse that some one ended up with the other person dreamor selfishness for the same reason.
...maybe because they them selves are not happy...