I'd say she should just.. keep acting normal. The weirder you act, the weirder things get. If a person behaves like something's wrong, it will look like something's wrong. Don't acknowledge the awkwardness, and it should die down.

Either that, or just have her ask him out or something. Dancing around things and making huge deals out of the smallest mistakes never helps. Even if he says no, it'll probably still be better than if he finds out through someone else. It'd be easy to take that step back to a regular friendship, without all the drama and manipulation and bleh.

... And I might just be overly moral and ridiculously patient, but. In my mind, if someone really cares.. they won't get jealous. Or should try not to be, at least. Jealousy implies you want what you want, not what they want. And attempting to incite jealousy isn't exactly a great thing to do either.