I think you also have to take into consideration that your plans, however laid out, probably will not work the same way when actually applied to your lives.
I'm in a situation right now where my husband has a girlfriend and when I once said I'd be totally ok with it and wouldn't even bat an eyelash, I now feel differently about. I'm still not sure what it is I feel but I know it's not what I initially thought would happen.
I think it's a work in progress. Lots of talking, listening and open mindedness.