This sounds really tricky. This is the situation I was in with my DH (as in I was your wife in your situation) and I said that I thought he should explore other options and I meant it. We had an issue because he kept saying he didn't want to do that, but then he 'tested the waters' behind my back without communicating about it which was not good.
I have also been in a situation where I was in a virtual relationship with someone who said that their situation was that they had 'implicit consent' from their wife, and it turned out they did not have the same understanding and everyone got hurt.
My advice would be to communicate about this as openly as you can. Be honest about what you value and want from your existing relationship, and explore what she might be comfortable with in terms of you looking for connections outside of your marriage. The Non Escalator Relationship Menu can be really helpful for this, to look at boundaries.
If you can, really focus on listening to her, and try to understand that a) what you would be happy with if you were in her position will not be the same as what she is happy with, and b) the situation will be fluid while you both get used to how it feels.
Some people say go ahead, but never the same person twice, or no overnight stays, or drinks are fine but no dinner. Others might say please try to form something stable so that there's no emotional up and down. Some will say they want to know, others will say don't tell me unless...
There are many different ways this can work, and many where it can go wrong. I firmly believe that the key is honesty and listening. Don't make assumptions.