First one is undoubtedly the best one of this trilogy. Usually is the case with all media, they manage to miss the mark on what exactly made it popular and it just degrades from there in subsequent iterations.
I put some of these through Google Translate, and it's a lot sweeter than the art might suggest. When she learns the blonde is also a futanari, she tries to get into her pants with mind control, but gets told off for using her powers to just fuck random people like that. The main character secretly feels conflicted now, since she's been doing exactly that all along. But they agree to take care of each other's needs. The futanari blonde is a virgin, and the main character has never been penetrated, so they take each other's first time. They agree to travel together, as it turns out the blonde's libido is apparently more than enough to satisfy the main character.
@MilkmanDan thanks for the short explanation. finally she realizes that she’s been doing the things that a man often does in stories were they use hypnotic powers to force women into having sex with them. which makes her feel like a jerk. now that she’s learned her lesson, she’s sticking with fucking only the blonde from now on.