Teen Dating: Obsessive Relationships
Don't butt in yet. I would first commend her for keeping her grades up and not neglecting her extracurricular activities. Save your concern for when and if her grades begin to get worse, her extracurriculars start being neglected or you see other signs of trouble.
It's normal for teens to explore relationships and to initially be consumed by them. The high usually lasts three or four months and then wanes. And sometimes they're hurt during the breakup.
We can't protect our children from pain like this, but we can be available to support them when it occurs and let them know they will survive and even grow from it.