Originally Posted by Derbylicious
Except when you don't know someone that well it can be hard to tell if down the line they will continue to behave well and honour the relationship. I trust my husband to do what is best for 'us' but until I know the new someone well there are some boundaries in place to prevent some of the drama that can happen. That's not to say that the boundaries aren't negotiable, it's just a starting point to work from where everyone currently involved is comfortable.
Negotiating boundaries within a relationship that's forming or already formed is perfectly reasonable. Setting boundaries for a relationship that doesn't yet exist isn't so much. At least not for the person that may be entering that relationship.
It is completely reasonable for couples to have agreements for what they consider to be acceptable within their relationship. But when those agreements start to be about what's acceptable within my relationship, then I have a problem. I'm not saying that there shouldn't be boundaries. I'm saying that creating boundaries for the sake "protecting" one relationship against another can be problematic. Getting involved with a new partner is a gamble any way you look at it. But partner selection is a skill, and not a terribly hard skill to learn at that. I would trust that my partner can recognize when a potential partner is going to cause harm and make the choice that honors what we have. I don't see the need to set up an outside rule that makes sure he or she does that.