There are additional requirements in addition to the final stat requirements. For example, if your daughter has the appropriate stats, a demon will appear before her twice and ask her each time if she will be their queen. She must agree both times in order for this ending to occour. You can tell if the demon is close to appearing if your daughter stats seeing bats.
After your daughter has agreed to be their queen a second time, she will cancel all dates that she had with any man; this will caus a drop in their orb level, although this drop can be corrected. She will also stop receiving invitations for dates except for special occaision invitations.