It sounds like the Ghost wants Hamlet to break up a fight between Gertrude and her struggling soul. Like there’s her soul on one side and Gertrude on the other and if her soul got a chance, it would take Gertie right out. So the Ghost is trying to save her.
But despite the Ghost’s supernatural origins, I’m not sure he’s assessing the situation correctly. Gertrude is likely not in the middle of soul struggle. She’s probably not trying to work on a moral problem. She’s probably not wondering if she should Be Or Not Be in this moment. She’s probably not examining her life’s choices, wondering if she did the right thing right about now. No. Right now, she’s watching her son talk to the wall as if it were listening. She’s watching her (only) son fly off his rocker.
I doubt there’s a fight about it all. She’s probably just concerned.
The Ghost may come from beyond but the still might have some trouble reading his wife. It’s impossible that this could have been a problem in their marriage.