My intention was not to offend anyone when I limited the question to heterosexuals. Platonic relationships between people of the same sex is usually assumed by society unless presented with countering evidence. Heterosexuals however who claim to have platonic relationships are viewed with suspicion.
It seems most people who have responded to the question agree with me that platonic relationships are possible. However, in my RL experience, society resists the idea. I've had very few close female friends but I've had several close male friends and I've lost every single one because people can't accept that our friendships were genuinely platonic. The friendships are always attacked with vicious gossip. That's fine I can handle that. Eventually, my male friends become seriously involved with a woman. The woman always says that she is okay with our friendship. I deliberately conduct these friendships openly to avoid rumours but they are always there. Eventually, they marry and the edict is delivered by the wife - the friendship must end. Now, I fully expect the friendship will change but, end? Really? I cannot see the logic behind it? Not to mention the cruelty? I can't imagine demanding that someone should discard a friend? I miss my friends so much. Migration has taken the rest. Life is so hard and I feel so utterly alone.
Sigh. It is really such a hard situation, you are right.
The thing to keep in mind is that the wives of your male friends cannot single-handedly end your friendships. The men have to be agreeing to their conditions. Why are they agreeing? Presumably because they desire to maintain the intimacy of their primary relationship.
I don't know if this is about logic.
I value your choice to keep the relationships open, but I'm also not quite sure what that means. Does that mean that everything that is shared between you and your friend is also shared with the spouse? Or does it just mean that you're not hiding the fact that you have a friendship with this person?
I believe that intimacies shared outside of and separate from a marriage relationship weaken the marriage relationship, or at minimum create that risk. That is not everyone's experience, certainly, but I do think that everyone has the right to set the boundaries they are comfortable with in relationship.
I think the issues for many comes because a marital relationship is generally seen as the most intimate of relationships. Relationships do not survive without tending. In order to tend to the intimacy of that primary relationship it is important to make sure that the nutrients that primary relationship needs to survive are not taken up by other things growing nearby. Your relationship with your male friends may take up resources that weaken the primary relationship. Again, keep in mind that these men chose women for whom this would be an issue and they then agreed to the requests made by these women. This is something a couple has decided to do together in order to protect their relationship.
I understand that you don't see yourself as a threat to their relationships, and quite possibly you are not, but many women would be. A decision was made within these relationships to honor to the best of their ability the nurturing and protection of that primary relationship even if only by minimizing the risk.
I don't know what advice I can offer you regarding the situation you find yourself in, but I can say that I do understand and respect the decisions your friends have made. If I had a friendship with a man who decided to end it because he wanted to protect and nurture his primary marital intimacies, I personally would value his choice even if I felt sad at the loss of the friendship.