Agreement to let her decide on sleeping with others

Hey guys,

I'm searching for some text that you can tell your girlfriend or wife, which basically gives her the guilt-free permission to do what she desires if she is not satisfied sexually in our relationship. However, I am not talking about openly communicating the want to be a cuckold, that may be something for later. But rather to take those initial blocks towards it away. Plus I would still want to relax with her too. It is something to let her know that I would not see her as slutty or whatever else, for following her desires she needs and deserves to feel like a woman - talk along those lines. That I would not view her differently if she desires to relax with another man or wants to flirt if at the end of the day I am still the one she wakes up the next morning with.
So it has to be something very subtle...
Of course it can include that if she can't be satisfied by me, and if she does decide to relax with others, that this does not mean that I can do the same. In other words, she should not feel that I am simply telling her this to get rid of my own guilt for wanting to relax with other women other than her.

Any thoughts? Anybody put forward something in a lovely worded way to her? Chat/MSN I think is great to tell her this.