Do you think I have to start ghosting my girlfriend?
Is there a reason why you're going to ghost her?
In a relationship? There better be a lot of reasons.
So there is a lot of issues going on in the relationship, that's unfortunate. That being said you shouldn't ghost people, it's not nice, just tell her you need to move on.
It's not nice, it's the quickest way to end a relationship.
It may be, but didn't you care about your girlfriend a lot? How hurt do you think she's going to be when you just disappear? How about just breaking up like normal, so there won't be any lingering regrets?