A curious thread for me and this is speaking as a guy who doesn't find sex that important in my relationship. As such and I find it hard to speculate how sex dominates the spectrum of a partnership, is there a way of looking at context here?

You've said that she's a good person, that she's the woman you want to raise your children with... that you've been together for 15 years (which denotes a hell of a lot of commitment in this day and age)... is risking all of the positive things you share together worth sampling potential forbidden fruit to fulfil a desire/curiosity (god forbid the person you had an affair with didn't get an orgasm either... there would be an element of irony in that but I'm not trying to demean the question you're asking).

Also, you've mentioned that she is very disciplined... that's a quality that denotes denying oneself of certain pleasures to achieve other goals or keep things at a manageable state... finances, diet.... relationships.

Could the above be something that could be used in this context for yourself?

Don't get me wrong, not judging you (at least I hope non of the above appears that way)... you have your own life and decisions to make and fair play and good luck to which ever path you choose... I guess I just want to draw attention to weighing up all the variables before taking the plunge.

Window shopping is one thing (as well as fantasising)... actually crossing over the bridge to see if the grass is really greener is another hehe.