Most people know the story of Pandora's Box (and lets leave aside the fact that its another mythology where a woman brought evil into the world) and how once opened the contents could not be returned.
Polyamory can be like that. Many couples give each other veto power over relationships or the poly experience, I know I did with James when we first started polyamory. We agreed that we'd be able to veto each other's prospective partners if one of us saw an issue. However, one a relationship is opened to polyamory it is very hard to put the contents of that box back inside without resentment and the original relationship coming under threat.
In the end, the veto power really should just be a security blanket. It should never be used because once you've let yourself and your partner start experiencing other things, you cannot return to the status quo because that has forever changed. This is one of the scary things about polyamory and at the same time one of the best things. Learning more about yourself and your partner and growing are good things. Finding new people to be involved with is both a challenge and a rewarding experience. There are positives and negatives about new relationships, just as they are when you are monogamous. People generally do not give up on monogamy because they have a bad relationship experience, but some will want to give up on polyamory for the same reason.
I know how hard it is to watch your partner start a relationship with someone else, or know that they are falling in love with someone else, or that they are having sex with someone else. I've been there and lived through the insecurity. If your relationship is strong and built on good foundations and you both are committed to each other then polyamory will most likely not damage your existing relationship. The insecurity is a bitch, but I came out on the other side a much stronger and centred person than who went in.
So, if you and your partner have opened your relationship up to polyamory can you shut it down again? Certainly not easily. Really it should be a decision that both of you make, the same way that opening up your relationship should be a joint decision and not the decision of one party. One party exercising a veto over polyamory or a relationship is very likely to cause resentment from the other. I certainly hate being told what to do versus negotiating and discussing an issue together fully as if I am an equal partner in the relationship.
Personally, I'd be more afraid of that resentment from a partner over the fear that my partner might find someone better than me, which is just my insecurity and far easier to solve than a partner resenting a decision I've taken over their life.
If you are struggling with polyamory TALK to your partner about your issues and/or talk to someone else about it. Reacting by shutting everything down and attempting to regain the status quo is never going to work.
