Engaged but thinking about mutual outside experiences...

Ok so based on some of the negative comments I received I think I may not have said things or explained myself correctly. I shouldn't have said basically I want to sleep with someone else because I'm not planning to be with anyone else. My concern is that both my fiancé and I may have regrets down the line that we didn't have any other experiences so should the opportunity arise for either of us I want us to do what we want/feel without the guilt of repercussions in our relationship. I'm secure enough in our relationship that should he want to experience something else I would understand. At the end of the day we're coming home to each other and love each other. I'm not saying we would definitely ever be with anyone else but if it happens I don't want it to be cheating and lying. Things happen and I want us to both be comfortable if it did. Does that make sense? What I was trying to say is I have these thoughts/feelings but I don't know how to talk to him about it without him thinking I'm getting cold feet or that these thoughts some how diminish how I feel about him. Like most of you said marriage is forever and I completely agree as does my fiancé otherwise we wouldn't have taken it so seriously as to wait as long as we have however relationships are not one size fits all. Am I saying this right? I'm not some crazed person who is just jumping into marriage and wants to cheat on their SO. If we talked and he said I'm not comfortable with even the idea of that for either of us then done deal. But I feel the need to talk about it with him and I just don't know how.