Hearing Her Moan

The summer nights are becoming nicer by the day. Living in the northern climate helps one appreciate pleasant weather. And that's what me and the wife did last night. We had a small fire and a few drinks relaxing in the calm night air. After a bit my wife decided she was ready for bed. I wasn't quite ready so figured I'd watch a movie.
At one point around 11pm I went out to have a cigarette.  (I don't smoke in the house.) In the house I am almost always nude. So to go outside I threw on a pair of loose fitting boxer style PJ bottoms. I went to the back yard where the last bits of the fire was just on its way out. Sitting there I decided to take off the boxers and enjoy the night how nature intended.
My neighborhood is not very private. And in the winter when the trees are bare of leaves you can see into everyone's yards. But at this time of year the tree canopies almost completely hide my yard from view. So from time to time I take advantage of my little bit of yard.
So there I was enjoying my cigarette, mindlessly scrolling through social media.  When I heard what I thought was a woman's moan. It was very faint so I dismissed it as a squeak from the yard swing I was on. A few minutes go by and again, a couple of soft moans. Curious now I start to listen closer.  There it was again. I was sitting just below the window where my wife was sleeping. At this time of year either everyone's windows are open or have air conditioning units in them. Ours were open. 
We often fall asleep while watching something so my first thought was it must be something she fell asleep to. The moans were getting a bit more regular. And a bit louder. My dick started to get that familiar tingle as my mind was trying to figure out what or who was having such a nice time. It wasn't the tv, it was definitely someone. My wife doesn't watch porn so that wasn't it. It wasn't my wife's voice so it wasn't her masturbating.  
Then a good loud moan followed by a steady rhythm in her voice, it was the house next door. Their bedroom window was also open. Now that I figured out where and who, my hand naturally found itself wrapped around my growing shaft. It was a pleasant situation, already being naked outside and her voice echoing the pleasure she was feeling.  Plus there was still the light glow of the embers in the fire pit. 
The disappointing part of it was that I could tell she was about to cum. I was hoping that they had just started but that wasn't the case. She was done. And I had just begun.  I sat outside for a while longer anticipating a round two. After about 10 minutes or so I decided to go back inside and finish off with some porn because the drinks earlier were holding me back from a quick relief. I really hadn't thought about jerking off that night. But I couldn't pass up such an inspiring opportunity.  And the porn helped put me over the edge.