Well don't know how it'll look when I'm married, but that's a part of it all.
In some marriages Celibacy is something both partners wants, while in others both want it to be open. So cases where just one wants an open one seem not too rare... I used to be against open relationships, but I notice they do have a lot of good things, but they requires a lot of trust.
I had to break up with my last girlfriend, cause she wanted an open relationship. I just didn't feel able to stand the thought of my girl having sex with another guy... I also wouldn't feel ok doing it with another girl... I was ready for a compromise by allowing both of us sex with people of the same gender (she was pretty bi like me), but she wanted to be free, so we just stay friends now.
You want an open relationship, for you it may be like the greatest thing in the world, but your partner might not like it. So I advice you to make the best out of this situation............. yeah that's the best tip I can give, sorry!