Like MMArio I have always assumed that the father was pissed because she ran away with anybody. The inferior social status of her partner made it even worse but also showed that she really did love the guy as she was willing to put up with hardship in order to be with him. The ending just restates the proprieties, this was a one time deal so we'll let it pass, so that other young women will be less willing to run off with poor young men.