Well if you were perfect, you wouldn't need a Master. I can't think of anything more boring than having a girl who did everything exactly right all the time.
My girl is going through a period where she finds it difficult to meet her responsiblities. We got to the point where I said we need to suspend the D/s side of our relationship for a while & just be friends while she gets her life sorted out.
Any kind of relationship between two people has it's ups & downs- it's just human nature to go through different phases. Part of the fun is to be flexible enough to keep up with it all.