I remarried when i was 38 and gained two stepdaughters. The oldest moved out about two years into my new marriage. The younger one, Dena, just turned 18 the year her sister moved out.
Dena wasn't super sexy or anything, in fact she was kind of chubby and I never looked at her other than an annoying step child....until the summer she graduated.
My wife worked nights and left the house about 10pm each night. Dena was a night owl so she was usually up pretty late. I usually waited about an hour after my wife left and would shut my bedroom door and masturbate. Yes, after only a couple years of marriage my wife just wasn't putting out enough. I've always had a very strong sex drive and at 40 it was stronger than ever.
When i finished jerking off I would clean up and open my bedroom door and go to sleep. My wife leaves the bedroom door open always so I would be sure to open it back so she didn't wonder why I had it closed.
I should tell you here the layout of our house. Dena's bedroom was the only room upstairs and the house only has one bathroom. So if Dena needed to go to the bathroom she would have to come downstairs and walk past my bedroom to get to the bathroom.
One night I decided to just leave the door open while I beat off. I would be able to hear Dena coming down the stairs so it would give me time to cover up. It wasn't like it took me forever, she might interrupt once before I would get off, no big deal. Just cover up, wait and then resume....easy.
So I get the boss out and start schmoozing him with the bedroom light off and the door wide open when sure enough I hear footsteps coming down the stairs. I covered myself and instinctively looked at the mirror on my closet door which reflected the view down the hallway. Here came Dena down the hall and just as she passed my door I noticed her slow slightly and take a quick peak into my room. From where she looked in she would have only been able to see me from the chest down. I suddenly realized that my heart was beating faster and I was excited thinking that just a few seconds before she looked in, I had my cock out.
The thought that she might have caught me jacking off made me very excited and got my adrenaline running. As soon as she was done in the bathroom and went back upstairs I pulled my cock back out and immediately shot a powerful load of cum all over my stomach at the thought of Dena catching me.
The next few nights I was able to get off without interruption and decided it was safe enough to keep the door open and lights off.
About a week after the first incident it happened again. I was rock hard and stroking myself off when I heard the footsteps on the stairs. This time something made me hesitate and as I looked at the closet mirror I saw Dena slow and glance in my room just as I was covering my cock up. Did I see her hesitate? Did she see my cock? As the bathroom door closed I could feel my heart thumping in my chest and before I could grab my cock, cum is shooting out under the blanket. I haven't climaxed that powerfully....maybe ever. What a mess it was under the blanket. As I was trying to figure out how to clean up the mess I heard Dena come out of the bathroom and go back upstairs.
I got cleaned up and laid there thinking about what just happened. Did she see my cock? I definitely think she hesitated. I wasn't fully watching her expression. I couldn't believe how much it excited me thinking she saw my cock. But did she see it? I decided to check something. I got out of bed and went to the hall then looked into my bedroom from where Dena glances in. It was dark. I could make out shapes but no way could she have seen my cock. Maybe she noticed movement. I decided to find out.