I know for myself that watching the act was just as thrilling as getting invited. But I have always been rather secure in my sexuallity too. My ex at the time was mainly wanting my friend by herself and only me watching so that way I would do anything with my friend. But she finally got into the whole act and got really excited and that was when she was secure enough to invite me.
Glad that I could help, and feel free to PM me whenever.

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Allow the Shade of the Moon to envelope you in it's mist and caress you