My friend's parents marriage is about to hit the rock(divorce) and this is really destabilizing her in all areas of lives, please advice 😔 ?

I believe not only in what I see but also wat i don't see.
Depending on how deep it has gone, but no matter what try to hear each of your parents side of the story,you can then see for solutions that is how you can help them tell them the consequences of their unwise action.
The most supreme solution to your problem is prayer,pray ceaselessly for your parents to come backand the love they saw when they were about to marry.
If the marriage should eventually hit the rock then don't forget to pray always whether or not the marriage crashes you can also love to come by finding what each of them love then make them do it for another, you can also buy love novels, you can also create love designs and their pictures which they were together and add a love text make about ten copies every morning, make sure they don't get negative advice from outsiders.
I think this is the best i can offer.