I see no problem with this

"Yeah you can be big spoon tonight" I respond, "I'm so tired, it's been a weird day".

Jenny just smiles and gets into the tent with me, we both get naked and I lay on my side. She wraps her arms around me and I feel her big soft breast press into my back. Then she presses her groin against my back, I can feel her cock between my cheeks, she wiggles and nests between them.

Before I'm allowed to drift off she whispers into my ear "remember I have dibs on your butt". "W-what, I never agreed to that". I respond.

"You promised I would get to go first on your butt, remember?" she reminds me. Oh right this morning. Now I remember.

"Yeah but now? I mean what's the rush" I try to get out of this situation. Meanwhile I feel her cock getting bigger and harder between my cheeks.

"The others are going to want your butt tomorrow hihi, the only way I get to be first is if I get it now. Pleeease?" She says as she wriggles her hip again, causing her cock move into a more dangerous position.

"What about lube, condoms? It's going to hurt" my final defense.

"spit into my hand", she holds her hand in front of my mouth, my defense is shattered, I know she's right. I spit into her hand "please be gentle, it's my first time".

She puts her hand between my cheeks and rubs my asshole with my saliva, she then spits on her hand again and rubs her cock. She then puts a finger into my ass, with her other hand she puts her thumb into my mouth. I suck on her thumb while she gets ready for two fingers. Slowly working up to three fingers. After minutes of fingering my asshole and stretching it out she's ready. I'm ready.

She positions her cock at the entrance and slowly begin to apply pressure, at first I resist but then I feel my asshole give way to her cock. It's like a pop, once inside she pushes it further in with relative ease. The pressure is immense.

"Shhh shhh shhhh, It's ok, I'll sit here and let you get used to this", as she says this I'm sucking hard on her thumb. After a few minutes the pressure seems much less, like my muscles have relaxed. I tell her I'm ready.

She moves her hip back and forth slowly, her cock gliding in and out of my ass, after a while I feel a sensation in my penis, is she going to make me cum? My cock gets hard and her slow movement start to feel pleasurable.

"Harder" I grunt. "Ok sweet boy", she starts moving faster, deeper, the pleasure increases. I feel her cock get bigger and harder from the increased stimulation, she whispers in my ear "I'm about to cum". The knowledge that she's about to cum in my ass is deeply arousing, combined with the pleasure from stimulating my prostate the effect sends me over the edge. I cum harder than ever before, right when I do she moans and pushes her cock as deep as she can, I can feel her cock pulsating in my stomach. While cumming she grabs me with her arms and hugs me tightly.

She whispers "I wish you could be mine" and we both drift off, her cock still in my ass.