I kept quiet and let her make her own decision, but I think the outcome depends on what’s happened before.
Not if you keep quiet...I'm not 100% sure but if you don't intervene I think there is only one possible outcome...the one that involves stabbing. And yeah you can continue the romance. But if you intervene and fail the persuasion that may end your romance right there, also not 100% sure but at least that's what the narrator seems to imply. If you don't intervene and just let her have some happy stabbing time then you can also continue the relationship.
