counter blackmail. i'm sure if you've known her that long you probably know something about her that could ruin her. it's called mutually assured destruction. other than that, i dunno. 

try to seperate lust from love, you could just be lusting after this 17yr old and in the end you might want to go home to your girlfriend everynight.....it's hard wish you the best!

You know, it could very well be lust as CaliforniaLovin made mention of.  But, then I tend to disagree in one aspect when it comes to situations as this.  Yes, you have been together 6 years.  But, sometimes... Sometimes, you have to know when it's time to call it even, a draw so to speak, and just end it.  If you are thinking about cheating on her, then in alot of cases the relationship is over.  I know you said that you haven't had sex.  But, look at how long you've been together.  It's normal for every relationship to have a dry spell.  If the love is strong enough, the companionship is usually what matters most, the sex will find it's way back in the bedroom eventually.  Take that into consideration.  

Are you still with for the being with her?  Or is there still that enduring love, where you think about before you fall asleep and you think of her first thing in the morning.  When you were talking to that young girl, did you feel even the slightest shred of guilt or the nagging feeling of something just not being right, that there was something off?  Did you for instance, feel awkward?  The list goes on, but if none of those relate to what you felt during that time or even now.  

Then it seems you have the answer and have known it for some time.  It isn't that there is anyone at fault here, it's just your heart is no longer taken.  Just wasn't meant to be...  And yes, there could be a big argument and alot of crazy emotions involved with a conversation like that.  But, if you feel that way...  It's very likely, pretty much given actually, that she has known herself for quite sometime and probably feels the same way. 

I wonder if this could possibly be a way for the two of you to actually work things out. This is the perfect opportunity for both of you to look at your relationship and determine where to go from there. "Lesbian Bed Death" is common, but it doesn't have to be forever.

I don't know how beneficial it is to get with someone so young. While clearly from your experience, someone that age is capable of having long-lasting relationships (since it looks like you were probably around your neighbor's age when you and your current gf got together) I think you would agree that down the road, you may realize that engaging in a committed relationship at such a young age might leave you wishing you had enjoyed your adolescence a bit longer.

 

p.s. we broke up and i am now seeing the 17yr old... i follow my heart