I feel like the people saying that Mei has regressed have, at the very least, misunderstood her character. She was never a "sexual predator", she was simply mimicking what she had seen (and done to her), "monkey see, monkey do" if you will. From the start, it was stated that she never enacted on her desires, always only focusing on being the obedient girl she assumed it was what it was expected from her.
Now thanks to Yuzu and everything they went through, she's finally enacting those desires, but she has absolutely zero ideas of what she's supposed to do, so her idea of taking things one step at the time is because she's learning on the fly alongside Yuzu. If anything, both of them are showing a maturity they lacked in Citrus, with Yuzu learning to be less impulsive and reigning in her overwhelming love for Mei, while Mei is slowly embracing and growing comfortable with showing her affection, while juggling her responsibilities as future chairwoman of Aihara Academy.
Yes, Sabu could have them making out and fucking like rabbits but that would be completely out of character.
