Actually, you might consider suggesting that you go up and spend time with her. It made a huge difference for me when I was stressed out beyond measure when I was in college. My mom and I baked meatloaf and baked potatoes. I'll never forget how much that made me feel better in the long run...
I went through the same thing as your daughter with my high school sweetheart who was 2 years ahead of me in school. He dumped me for the college girl scene and I was miserable back home my high school senior year. My mother gave me the following poem:
Forget his name, forget his face
Forget his kiss and his warm embrace
Forget the love that once came true
Remember now there's someone new,
Forget the love that you once shared
Forget the face that had once cared
Forget the time you spent together
Remember now he's gone forever,
Forget you cried the whole night through
Forget him when they play your song
Forget how close you two once were
Remember now he's chosen her,
Forget you memorized his walk
Forget the way he used to talk
Forget the times he was mad
Remember he's happy instead of sad,
Forget his teasing, gentle ways
Forget you saw him everyday
Forget he made your dreams come true
Remember now she loves him too,
Forget the thrill when he walked by
Forget him when he made you cry
Forget the way he spoke your name
Remember now he's not the same,
Forget the way he said he loved you
Forget the way he kissed and hugged you
Forget all those nights when he held you tight
Remember now he holds her tonight,
Forget all those sunny days
Forget all those poems he made
Forget those times through good and bad
Remember he said he'd never make you sad,
Forget the games he played with you
Forget the times he stayed with you
Forget those cold, cold nights
Remember now he keeps her warm tonight,
Forget the way he looked at you
Forget you kissed the whole night through
Forget all you dreams came true
REMEMBER, that he doesn't love you.
Oh yeah, the poem made me cry, a lot, but I put together a poster with a lot of memories about him. Lunch receipts, bowling scores, pictures of me with flowers he had given me, funny cartoons that made me think of him, etc. In the middle of that poster was this poem. I still have the poster.
And for the surprise? He and I ended up getting married when I finished college (which is why I still have the poster.)
Of course, I would never have thought that we would be back together after he dumped me, much less married. I do believe that getting out there and dating other guys made all the difference in the world for me. He found out that I was dating and started coming back around right before I went off to college. That's what your daughter should do, too, regardless of whether it makes a difference in how he feels about her.
Even if her dates aren't interesting, she's out of her shell seeing "something else".
(Btw, I'm not recommending the poem right now... you know your daughter. It did actually help me, though...)