Will they be together forever?

ok, this is going to sound kind of mean. I like this girl alot, and she has a bf and they seem like theyll be together forever, and it makes me sad. shes 14 and he is 15 i think. god, im not liking myself right now, i want her to be happy but at the same time i dont want to see her date... so, do you think theyll make it, and be together forever? I do understand love and such, im 17. im sorry if i seem like a .