My family has some vacation cabins where we all vacation once a year. When I was much younger, myself (M) and a cousin (F) used to flirt. We would often kiss and make out.
One night while staying at the cabins, several of us cousins were hanging out in the cabin where she was staying by herself. Eventually, we all left and later, I snuck back over. I climbed into her sleeping bag and we started making out. I was feeling her perfect tits and fingering her wet pussy while she stroked my cock. Being that I was a virgin and not very experienced (she was a year older and experienced), I wasn’t sure how far things would go as I didn’t have a condom.
As we were kissing, she stopped me and whispered that she was on the pill. I knew then that she wanted me to fuck her. We both eagerly removed our underwear and I rolled on top of her. She reached down and guided my cock into her pussy. Not knowing any better, I slid into her all the way with one thrust. I can still remember the gasp she let out to this day. I started fucking her and it wasn’t long before I thrust deep and held my cock there as I filled her with my cum. I laid there inside of her for several minutes before rolling over and falling asleep. Fortunately I woke up before everyone else and snuck back to my cabin so no one caught us. We ended up having sex several more times over the years whenever my family would visit (we lived in different states).