I started breathing heavily. "Mmmm. Rub that hard dick between my cheeks."
Robert nibbled on my earlobes, sending electric flashes up my spine, while his cock dry humped between my cheeks. He whispered in my ear, "Let's go to the bathroom. I've got some Vaseline there." We walked to the bathroom, Robert's hand kneading my buns as we went. I couldn't believe how fast things had moved. Was I really going to let my best friend fuck me in the ass? It seemed unreal, like a dream.
In the bathroom, Robert put a towel on the countertop, and then pushed gently on the small of my back. "Bend over the countertop. Yes, that's a good girl. Oh, you look so sexy bent over and waiting for your man to fuck you." I leaned my chest on the soft, fuzzy white towel and looked at Robert in the mirror as he clicked the plastic lid off a jar of Vaseline and scooped a little lube out with his finger.
Robert moved behind me and leaned over, his warm chest resting on my back, his cock prodding between my cheeks. He kissed my neck again, sending a thrill through me, then planted kisses down my spine and then on my buttocks. One of his strong hands stroked my butt and inner thighs as he kissed me. He put pressure on my left thigh, and whispered in my ear, "Put your knee on the counter." Our eyes met in the mirror, and then I let him lift my leg up. I felt so open and vulnerable, one leg resting on the counter, the other planted on the floor, my butt cheeks opened and waiting. Then I felt a shock run through me as a Vaselined finger slid down my asscrack and started rubbing my opening. I gasped and then started moaning with pleasure. It felt so good, his finger running circles around my hole, rubbing the slick lubricant around my tingling asshole.
Robert whispered, "Rub some Vaseline on my dick. Get your boyfriend all ready to fuck his hot, beautiful girl." He scooped some more lubricant out of the jar on the countertop and smoothed it onto my right hand. I reached behind me, grasped his hard, hot cock, and started rubbing the lube over the shaft. He moaned softly when I kneaded his cockhead.
I looked over my shoulder at him, guided his cock to my waiting hole, and lined it up. "Fuck me, Robert. Fuck your girlfriend. I want your dick deep inside me." Then I turned and looked in the mirror again, watching his face tighten with pleasure as his cockhead pressed harder and harder, the pressure building. "Nnngh," I grunted in pain. "I don't think I can take it. It's too big. Please stop. Please stop."
Robert grabbed my hips for leverage and leaned slowly forward. "You can take it. Your ass feels so good against my cock. Do it for your boyfriend. Make him feel good."
"Aaaaah," I said, and then his cockhead popped in. I grunted and breathed hard, watching in the mirror as Robert's face scrunched up with pleasure. "OK. It's feeling better. Fuck my tight ass. Go slow. Oh, there. Yes. Yes. It feels good now. I love being your girlfriend. I love having you inside me, fucking me." I watched Robert's knuckles whiten as he grasped my hips harder and slowly forced his cock deeper and deeper into my ass, until he was buried to the hilt. He started pumping, and I felt a rush of thrilling danger as I gave up and felt the pain melt into pleasure, as I gave my ass to my boyfriend to fill up with his hard, eager cock. It seemed so surreal -- how did a married straight man like me wind up bent over the bathroom countertop with my best friend grunting, grabbing my hips, and sliding his cock deep into my ass? I grabbed some more lube and started to jerk on my cock.
Robert shifted his hands from my hips to my shoulders, getting more leverage and bucking for deeper penetration. "I can't wait. Does my hot, sexy girlfriend want me to cum in her sweet ass?"
"Yes. Take me. I love being fucked. I want you to cum. I want you to fill my ass."
Robert grimaced, trying to hold off. "Can I fuck you again? Can I fuck you tomorrow?" He plunged again and again into me, his thighs slapping against my ass.
I moaned as I felt my own orgasm build from the dual pleasure of my hand stroking my cock, and his dick rubbing and sliding and filling my ass. "You can fuck me anytime, anywhere. I love to get fucked in the ass by my boyfriend. I want to make you cum deep inside me."
"Aaaaah. Ohmygod, I'm cumming. It feels so good. Take it. Take my cock." Robert bucked against me again and again, riding the waves of pleasure, and then he stopped deep in my butt, gasping for air, his hot and sweaty chest heaving against my back. He reached around and grabbed my dick, pumping it.
"Ohhhh. Uh. Uh. UH." My sperm spurted on the towel under me, cumming harder than I'd ever cum in my life.
And then it was over. Robert lay on me, his heart pounding against my back, my cock growing limp in his fingers while his cock shortened and then slid out of my butt. Robert stroked my hair, kissed my shoulder blade, and whispered, "That was so exciting. I love fucking you. I'm glad you're my girlfriend." He squeezed my hand, and I squeezed back.
That was my first time making love with my boyfriend. But not my last.