Perhaps my opinion isn't very popular as I think when you're in a serious relationship you shouldn't be THAT close with someone of the opposite sex unless they're literally family. It's just weird, t's questionable, and it puts the other person in the relationship an awkward position that I think is kind of irresponsible to put someone in that situation. Your concerns are warranted, even if she hasn't shown any red flags. Sorry but simply put I don't think straight people of the opposite sex should be that close especially when you're getting married to someone. It's time to take things more seriously and not put yourself in a situation where you may feel tempted to sex with someone else because a marriage makes your life no longer about just you.

I realize some people may disagree with this or wouldn't be comfortable with it which is why I personally wouldn't date someone who is that close to another guy. And maybe you should have thought about that before you got married.

To elaborate more It's not jealousy, regardless of how much you trust someone it's just human nature to desire sex with someone you are emotionally connected with so you shouldn't even put yourself in that situation to begin with.

I digress, I think the only thing you can really do is talk to her about every feeling you have on the subject and maybe try to compromise? It's either that or bite your tongue and try to move forward but repressing your feelings never really ends up well..