I am the poster child for thinking I can take the world on all by myself. I don't like to look as if I am weak, and I hate feeling like I'm a burden to anyone, especially people that I care about. However, take a moment and place yourself in your Dom's shoes (or leathers, depending on how far you want to take the metaphor...lol):
If you were a Dom, and chose your sub, wouldn't you choose them based on the positives of thier personality and your belief in who they are as a person? Sure you would. Love is not pity, so give your Sir some credit and trust that he really does believe in you. If you think you're such an awful person, what does that say about your Dom for choosing you? Let what you feel for him carry over to how you look at yourself.
Let him be there for you, let him experience his sub at her most vulnerable. That's part of being a Dom and you want to deny him that? As a Dom, how would you feel if you were denied parts of your sub based on the fact that they didn't think you should see it or that you were equipped to handle them? Kinda' makes the position of Dom pretty impotent and pointless all of a sudden, doesn't it? I know I would feel like my sub didn't trust me and didn't think I could help, not th