No, I am not jealous of the relationship that they have. It's just that, things between the two of you are supposed to be special, like private. Would you want the whole world to know?
I think that, when I'm in a relationship, I prefer to keep many things hidden and private. If there's a problem, the only people who know about it is us. Only people who can solve it, is also us.
When other people know, it complicates things. Then the gossips start, and people can twist stories ever so easily.....