Try to look at the evidence you submitted and the interview the applicant had as objectively as possible. Then try to find better evidence that your relationship is genuine.
If you appeal, you need to show that the visa officer's decision was wrong. If you reapply, you need more evidence, and also different evidence.
Appeals take a long time. And if you lose the appeal, it is extremely unlikely you will be able to successfully reapply. This is because the appeal decision is considered final (unless you further appeal to the Federal Court of Appeal - and not all appeals are allowed to even be heard there). So if you reapply after a lost appeal, the visa officer will probably refuse the application because of 'res judicata' - which means 'we have already decided this case'.
Thanks alot
I would just reapply. But you need more and better evidence than the first application, or it will just be rejected again.