It depends on whether you see any alarming or harmful behaviors in her. Is she still getting up to go to school, eating, doing homework, seeing friends? Or is she holed up in her room 24/7, crying and withdrawing from life?
Sounds like he is older than she is and may be maturing or at least emotionally prepping for going away. It probably hurts her to know that he's been planning this for some time, but at least he didn't let it drag on, using her for entertainment or companionship until the last minute. He's looking ahead to his studies, but also to his involved social life (guys and girls) in a residential setting. Wisely, he saw how hard it is to maintain a relationship with someone back home.
If she sees him in the halls, that can be so tough. On the plus side, she's still in the middle of the school year and surrounded by other friends and activities. I'd help her stay busy, not to deny the hurt, but to prove to herself that she can go on. She would have been pretty date-less next year anyway, so now she's getting the jump on that and looking around for other things to keep her busy. If it helps her to hate him (a little) in the short run, that can be beneficial because anger can be strengthening ("I deserve better than that treatment" and so on). But if it eats away at her because she thinks she can change him or win him back, that's a bad thing.
Some friendships aren't meant to continue forever - people grow and change, and it's okay when they run their course. Sometimes there's a break-up, and other times people just kind of drift apart. So, what has she learned about herself in these 6 months? Did she feel she was valuable and attractive because a boy thought so? (Not a positive.) Or did she learn that she is a good and loyal friend? (Definitely a positive.) If she has to learn that things at 16 aren't forever, that's okay - hard, but okay.
I wouldn't focus too much on "You'll find another boy soon" (because maybe she won't, and because it's demeaning), but more that she's a lovely person and a good friend and that there are plenty of people (groups, both genders) who enjoy being with her, and here's her opportunity to share her good self with them.
And otherwise I think you can let her feel the pain without feeling you need to be the one to fix it. The best thing for her is to be of help to others, and that can help pull her out of her funk and see her value.