I can't claim to be an expert here, as we haven't shared yet, though we've discussed it and role-played.
I don't agree though that it has to be an all or nothing proposition. It's like saying - well, you let your wife go outside the house unattended, so if she ends up fucking someone, you opened the door and now you have to accept it. If you agree to watch the kids every Thursday night so your wife can go play tennis - now you have to accept it if she decides to play tennis 7 nights per week! That's just silly...
People break up, fuck around with other people, then get back together and resume monogamy all the time. Surely its possible to also enjoy extra freedoms within a relationship, within certain bounds?
You can craft whatever agreement works for your relationship, that feels like a reasonable compromise and satisfies both your needs. Will it always be easy for both people to stay within these boundaries and ensure the other person's needs are being met - no, of course not... being faithfully monogamous isn't easy either or there wouldn't be so much cheating.
While some dudes on here are betas who get off somehow (sorry, no judgement if you like that, I just totally don't get it) on being sexually neglected and deprived of attention from their partner, there's certainly other's of us who aren't into that. If I felt neglected and my needs weren't being met, why would I want to continue to remain in the relationship, let alone allow my wife all these extra freedoms that she wouldn't allow me?
If you continue to feel like you're giving more than you're receiving, resentment will slowly grow and sour the relationship. The exchange doesn't necessarily need to always be equal (if that can even be measured in these sort of situations), you have to feel like you're getting enough and not giving more than you're comfortable with.
You need to be able to say - look, I enjoy you having some extra sexual freedoms and I derive pleasure from it too when I feel involved. It's important for me to reconnect with you at the end of the evening after you've played. Spending the night makes me feel too uninvolved and uncomfortable. It's a bit too much right now and I want this to remain fun for both of us.
She needs to either accept that she already has pretty generous freedoms and feel satisfied with that or find a way that she can make an overnight fun for you too, otherwise that just seems kind of selfish and bodes ill for the future health of your relationship. I mean, if my wife told me I could go fuck other women but each time I had to write her a 5000 word essay about how beautiful she is and give her a 3hr massage, I'd be like "where's a pen and let me start warming the oil."