My wife knows about my penis exercising.. For a couple years I kept it private, but she is very curious and in this case she'd probably have learned of it at some point. She is supportive of it, and I think she is more understanding part because I have also invested in jade eggs and other vaginal workout stuff for her. All in all I still think that it is private to an extent, sometimes I have her give me head while I practice kegels in my
cock ring which gives me variety from watching so much adult entertainment for this. She has noticed the changes in my dick and is excited when I get it thick before playing with her. The negatives to telling her is that I can tell that she just like most women will secretly fear me enlarging my penis so that I can fuck other women... still doesn't stop me though. Guess it depends on what your relationship dynamic is, but I honestly think that most women don't need to know about this, American women tend to be very judgmental and I think its good for men to have a space in their lives that is not for womens thoughts to be on.