<human>: Can you condense the text into a few key points?

Throwaway account.

As a brief preface, this post was brought upon by listening to the 2012 valentine's day episode of This American Life.

My girlfriend and I (I'm 24, she's 23) have been dating almost 2 years now, and we were very close friends for years before that.  She's my closest friend and we have a relationship I'm entirely comfortable with; we keep each other busy, have an active sex life, etc.  The idea of spending my life with her isn't as far fetched as it may have seemed only a few months ago.  We live together, have a pet...and my life is markedly better now than it was before we were together.  

There is, however, one hangup; she is my only sexual partner, and I'm worried as to what this could do to our future relationship.  The This American Life story detailed how two 30 year olds that had been dating for 10+ years decided to try a "sexual exploration" separation as a test to their relationship, ultimately ending in their breakup.  I don't want to break up with my girlfriend, but this is an issue that's been gnawing at me for a while now and I feel it's something I need to address.  What would be the proper way of doing this?  Or am I just suffering from the idea of greener grass somewhere else?

As a sidenote, she doesn't know that I was a virgin before we started dating.
<bot>: In a great relationship, however worried as to whether my lack of sexual partners will get in the way of truly embracing what I have.