It is established by Astofiel that the worshipping needs to be 100% without any doubt and full consent. he also explains the dangers of rushing things. Even using himself as an example.
Astofiel even explains that MC lacks the powers of a demon and is more humanlike.
he also gave MC a specific task that will take time, leading MC to gain power. Turning Meredith away from her husband is not a one day job. A good example is Maxime who was not ready to worship MC after 2 years.
It can mean, storywise, that after some time Meredith is struggling and maybe loosing her interest in doing these shots, what would make sense if MC is too fast pushing her.