I actually liked the Dahlia ending. It's perfect for her and the slave/mistress-relationship of two people in love with each other is well written.
Personally I can't understand the people complaining that it's not "femdom enough". Every mistress has her own taste and there is no reason for it to include pegging and chastity all the time. Femdom is about the power dynamic between people, not about the practice method they use. This isn't KG oder Moving Down where evil women want to enslave and break men by all means. This is about two people who are actually in love with each other and use it to spice up their lifestyle and relationship.
Also there will probably a way more "extreme" femdom-ending later anyway with ending nr. 07
But for Dahlia, the only thing I found quite stupid was the part