I've seen that happen with a fair number of married couples that thought they were happy going into polyamory, then find upon dating others that they were ready to move on, on good terms or otherwise.
It's important that couples do what they can to continue strengthening their relationship with each other while getting to know others if they wish to remain together. Bring as much of that NRE as you can back into your original relationship if you want it to persist. Go do new things with your husband/wife, workout together, have adventures together. Fall in love with each other again every day, or the new relationships may lead to falling out of love.
Last edited by turtleHeart; 01-10-2013 at 12:10 AM.