I agree that if your lady friends don't have any issues with it, then there's nothing creepy or cheap about seeing the person you love experience a thrill that you cannot give them.
The way I read it, I got the impression that maybe this was the "only" way you were allowed to be with women, and if you're comfortable with that restriction then so am I. Personally, with me, I insist that my husband NOT be present during sexual encounters with other women, because I would be thinking about him too much to enjoy myself with her. At least until I was more comfortable in my relationship with her.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker