Of the three friends, Jack had the most trouble getting used to his new body. While he learned pretty fast how to look and act sexy and enticing as hell, and get flocks of thirsty guys lust over him, when it came time to actually have sex it proved to be much harder than he thought.
It was so unsettling and disturbing to be fucked, and no matter how much foreplay he would have, he was just too weirded out to actually get horny, and so he almost always ended up having rough and unsatisfying sex just so he could get some points and move on to the next guy. That was not the best course of action to take.
In a matter of a day or two, his pussy had got so sore and aching that it was pretty much impossible for him to keep having guys ravage it as he did at first. He tried to make up for it by giving handjobs and blowjobs, and even using his huge bosom to milk dicks as fast as possible, but he realized that that was even harder and more uncomfortable than getting fucked, and that left him with only one option left: his ass.
If pussy fuck was uncomfortable and painful, having anal was ten times worse, and it took a while before his anus got dilated enough so that it got easier. But his friends were apparently doing much better than him, and he was in desperate need for points. He did not want to be stuck as a woman forever, and he was more than determined to do everything in his power to win the game. Even if that meant going through a very hard time. Maybe eventually it would have got easier. He was not going to let anything discourage him.