<human>: Condense the text into a few key points

I've been with my girlfriend for 5 years. She's wonderful, attractive, and our families and friends are intertwined. And I love her. 

However, I have been having reoccurring dreams about a younger sister of a friend of mine. A number of years ago I hooked up (made out) with this younger sister, but she was too young at the time (17 and I was 21) for me to feel comfortable doing anything else. I could always tell that she was attracted to me, and one night she had started making out with me while I was pretty inebriated. I didn't do much to stop her, but I did refuse to take it any further.

Since then we have always had a sexually tense relationship and have remained close since she is invited to a lot of things that my friend is involved with (parties, events, etc.) and I see her fairly frequently (every several months). Years ago we had talked about hooking up again after she was in college, but I have never been single since then. Now it's many years later, she's in her mid-twenties and I have been having a reoccurring dream where we sleep together and I don't know what to do. 

I don't want to break up with my girlfriend, but these dreams don't seem to go away, and it does feel like there is "unfinished business" whenever I see this younger girl. I will preface by saying that this is not an "attractiveness" thing. Both women are very attractive in their own different ways. And both have great personalities, although the younger girl has more of a wilder/sexy streak in her than my girlfriend. And maybe I find that somewhat attractive.

I am not looking for advice saying "go cheat on your girlfriend," that's out of the question.
<bot>: Have a girlfriend and have been having reoccurring dreams about a girl who I have "unfinished business" with.