Bad deal
It is never really a good thing for couples to try having an open relationship. Some people can get away with it and are ready for that, but the majority of married couples just can not handle such a thing. We need loyalty and a feeling of safety in our relationships after all.
Knowing that the person we love is out there somewhere with another man or woman and doing something romantic would drive us crazy. Just look how it tore this marriage and family apart. We would recommend couple counseling before trying an open relationship. Trust us, most likely it will not end well for you.