Granddaughter struggling with her parents’ separation

Presumably her mum was working a lot before the separation?..
...or is she having to work more now so they can maintain a home each?
...Or maybe it's the start of Panto Season which is gruelling and involves terrible hours?

I think maybe a "new normal" needs to be established for her somehow.
Maybe she can be taken to see mum after school or when mum has scheduled breaks?

I'm not sure from what you say where your granddaughter now lives. With mum, dad or you?

So hard to see this as a grandmother though. I think all you can do is be "stable" for her - and do not criticise mum!

I’ve taken sides in my daughter’s separation. Anyone else would too if they knew what my daughter was subjected to in her marriage. But it doesn’t sound as though this marriage, the OP’s son’s marriage, was in any way abusive. It sounds like the couple have grown apart. If the split is very recent, the granddaughter may settle down as time goes on, but whatever the other parent was like, the little girl will miss the life she had with two parents together.

Be careful not to criticise her mother in your grandaughters hearing. She will very quickly pick up on your negativity about her Mum. Whether you like it or not she is still her parent.
Do not take sides.

Lots of people get through with one good parent, and one quite problematic or mediocre. It sounds as if you are in a very good relationship with your granddaughter and that’s a real bonus. It’s sad to hear about a young girl suffering from depression in this way. I wonder if your granddaughter has a very good friend- sometimes families outside the immediate family can be a positive force too. Hobbies and activities might help your granddaughter too?

Presumably her mother has a contract to fulfil ? When it ends she might have more time and be able to negotiate a different number of hours next time.She might be just as upset Asher child but have no real choice at the moment.Give her some support ,she,s going through a tough time too .

You don’t say how old your grandaughter is ?
So many children come from broken families that she will not be alone She’s going through a time of upheaval and adjustment but she will adjust
Thankfully she has a good father (and grandmother) don’t be surprised that she’s missing her mum that is totally normal but she won’t stay unhappy she will adjust to this new way of life
Let her talk about her troubles as much as she wants encourage her to open up, without nagging, stay neutral don’t call her mum out for her behaviour just concentrate on the positives and be there for her

Granddaughter sad at mothers absence