Even if he was a trash healer, anyone in customer service would be fired for doing that in the view of the public. That guild receptionist would have easily been fired in real life.
This story sounds a lot like "Who Made Me a Princess". I suspect the father already had another lover and decided to abandon the MC since she did not look like him.
Good so far.
I am still hoping for a good romance in the story as well since it sucks when the MC doesn't get a good payoff for all of their hard efforts.
Don't forget they didn't let the sisters know about each other's existences for 6 years... That is 6 years of parental/maternal neglect. No wonder the original villainess became that way.