She doesnt really give you a choice

As you bring Alexandra to the point of no return, she makes sure you take every last bit of her cum. She quickly takes a hold of your head with her giant hands and presses it down on her cock. Her strength is insane, so your face is quickly mashed all the way down her massive rod for the first time. You gag out loud, as the 25-inch monster goes straight down your throat, poking at your guts. Your eyes start watering and your jaw stretches beyond its limits, but you try keeping your composure. Your nose mashes against her toned stomach and she starts grinding her crotch up against your face as she releases her first load. It goes straight down your throat and into your stomach, with you even needing to swallow it. It's hard to tell how much she cums, but she does so for a while, and you feel your stomach get filled up with semen. She sprays another giant load down your gullet, delivering it straight to your belly. She doesn't seem to slow down but gets even hornier. She lifts her legs up and crosses them around your head and neck, holding you in place firmly down on her dick. More and more cum gets pumped in your system and you start running out of air.

You attempt to raise your head from her crotch, but it's practically impossible. The weight of her legs is more than enough to inhibit you from going anywhere, and she doesn't seem to be planning to let you go any time soon. All you can do is experience the feeling of being ****-fed load after load of Alexandra's semen and waiting for it to end. After a few more minutes, your body passes out from the lack of oxygen. Blackness surrounds your vision and your mind is filled with images of cocks and cum, as you daze off to unconsciousness.

After an unknown amount of time, you feel something changing. What is it? You feel lighter as if some sort of weight is being lifted from you. A feminine voice calls out something, but it's foggy and unclear. A brightness starts fading around you and you feel your body again. There is still the weird feeling of lightness. Wait... lifted off... freedom... breath, you need to breathe you can move you can breathe YOU NEED FUCKING AIR!

You quickly regain your senses as your mind jump starts your body back to the land of the living. You realize Alexandra's legs are no longer holding you down, so you shoot up, letting her slightly shrunken cock flop out of your bottomless throat. As it does, you take a giant breath. Color floods back into your vision and the necessary resource for survival is restored.

"Oh, you're awake!" A familiar voice speaks up.

You see Alexandra staring at you, slightly worried but now relieved. You take in the scene before you and see a white, spunk covered cock in front of you. You remember that you were **** to swallow Alexandra's load and you can definitely feel it. You look down and see that you have a massive beer belly full of thick semen inside of you. You instantly burp from your giant-sized meal and can taste the salty bitterness of the semen as it comes up.

Alexandra speaks up again "Yeah, sorry I... kinda fell asleep and didn't realize you were still there. I don't know what came over me... Your throat just felt so good that I wanted to breed with it forever! I think you sucked me dry too..."

It's true! You swallowed every last bit of her seed, and you feel a sense of pride in doing so, even if it wasn't by your own free will.

The speakers turn up and you hear the voice of Alan. "Alright guys, pretty long session, but all in the name of science, right? You probably won't need to eat anything for a while now... maybe even a couple of days... Welp, that's all I wanted from both of you, so get back to your rooms and happy testing!"

Alexandra picks her massive body off the ground and makes her way to her room. You do the same. You wash out your mouth from the aftertaste of cum and burp from your meal.

You got the "****-feeding" ending with Alexandra.