Your wife is young, not dumb, and should be full of cum - she could easily pull many trains of horny, big (may I say black) cock.
I would like you to write out (and sign in front of witnesses) some amended wedding vows, giving your wife legal permission to take any lover she chooses whilst still married to you.
Then you should get a job in another town for a few months, and allow her to "play the field". By the time you get home again, she will be "firmly into the lifestyle" and fully confident to make sure you take over all the household duties when you are home from work.
You don't need to watch your wife having sex with other men, but it would be okay to listen to the sounds from another room. This will hone your hearing and imagination skills.
Seeing cum drippling down your wife's thighs is all the evidence you need that she is "having a really good time"....and your promise is kept that your wife is better off married to you instead of some macho man who would restrict her sexual expression.
Hopefully, all your best mates can be part of the trains, and they can give you a good ribbing from time-to-time over how lucky they feel to enjoy such a horny wife that you are not able to satisfy.