StoneElf, I don't believe anyone said anything about having totally separate lives and not acknowledging your marriage as important. Nor did anyone say that a married couple should keep secrets from each other and never know whom their partner is with. I did suggest that you could reach out to her, in fact. Poly is consensual, after all. You seem to have misread us.
The issue seemed to be that you thought a woman should ask you first before expressing interest in your husband. We responded to that, and I think most of us said it's not necessary beforehand but no one said you should never expect to meet her. That part is where a lot of variations exist, depending on the people involved and their preferences. In explaining my answer, I brought up the importance of autonomy, but that was not meant to imply that your marriage should not count as something valuable and solemn or anything else it means to you. I think that perhaps you might feel a little chastised and defensive about some of the responses you received.
But you wanted our feedback. Just bear in mind that these are our opinions and no one is telling you what to do, feel, or think. It is obvious you are a very intelligent and thoughtful person, so take whatever useful information you can from what people here share with you, use what you think works, toss the rest, or tell us we're all nuts!