star-crossed lovers
Two people in love who are forced to be apart by circumstances or influences outside of their control. A phrase popularized in its use by Shakespeare to describe the titular characters of his tragedy Romeo and Juliet. Any high school couple forced apart by where they go to college will likely feel like star-crossed lovers for the first week or so, and then realize that there's way more to life than an awkward adolescent romance.
star-crossed lovers
ill-fated lovers. I suppose that Romeo and Juilet are star-crossed lovers.