I'm happy to hear you've discovered something wonderful that you would like to have in your life and I'm sorry to hear that you and your wife have lost the magic in your marriage.
There's a general consensus in the poly world that your primary relationship needs to be strong and solid before you start adding other people to your life. At this point, even if your wife did give her permission, it would most likely only drive a deeper wedge between the two of you.
Right now, it would be good to focus on your marriage, either fixing it or deciding that it can't be fixed. If you decide to pursue a polyamorous lifestyle, that can come after you take care of the immediate situation. Getting together with another woman will do nothing to fix the immediate situation.
Gralson: my husband (works out of town).
Auto: my girlfriend (lives with her husband Zoffee).
The most dangerous phrase in the English language is "we've always done it this way."