When does breakup sadness become depression

[Puddingfortea]

My DD who is 15 was dumped by her boyfriend a month ago. No warning, no notice and now, no contact. She was devastated - they’d been together a year. She has cried lots since and she’s just not the same girl. She’s going out with friends and keeping busy but just says she’d rather be out with him. She’s still sobbing about it most days. Is this normal for a breakup or is this slipping into something more?

I'd say totally normal, losing your first love can be very hard. Still worth keeping an eye on though, because things should start to improve over the next few weeks.

It's good that's she lets the grief out.
The next stage will probably be anger
At some point acceptance will kick in and she will start ti feel better.
Let all these stages play out

If she pushes the anger down (anger going inwards) starts feeling hopeless and sorry for herself, this is depression.
But it all sounds pretty normal so far.
Keep supporting her and encouraging her to get out. Abs be there with the hugs and tissues- she'll get there.