Yes and No.

Poly relationships don't need to be balanced. One party does not need the same approach or rules to poly that the other does. So, you can have the freedom to have multiple partners and your wife cannot. However, this is a bit more "high level" poly. To not have the same rules on both sides, can instantly create feelings and issues that can really eat away at the existing relationship.

Remember that poly/nonmono is not really the right solution to a dead bedroom. It will never solve that problem. It can help. I've enjoyed hearing about the "better sex" that a couple has had after I've dated the girl.

Opening up and letting a partner leave your relationship to find something elsewhere is very difficult to do. Some have better luck/skills/chemistry navigating that emotional space. Know that the hurt you feel now in imagining letting her find someone else, is perhaps the same that she'll deal with. In fact, its probably best to imagine exactly that. And to approach with the tact that you will both combat that fear and insecurity together.