Re: Cousin Dilemma!
From what you have said - those two really like eachother. She should not tell him now...as I have a feeling fate will bring those two together. Tell her to be cool and patient. It will take a certain, special moment where they will both feel naturally comfortable in revealing their true feelings to eachother.
This exact story is what happened to my cousins. When people...even I would tease them - they would both get upset and offended but only because they didn't know that they both liked eachother.
Best of luck to them.
Oh and please do tell us when they both finally get together! :)