He gets the feelings of jail time and the almost yandere, but the college roster are just friends?
In all fairness, the girls in this world incentivized to act this way, to hide their true intentions.
The strategy is as follows:
First enter the orbit, then slip into DMs and hang-out with friend group - don't make any too obvious moves that would make him downright reject you (game over scenario) or be annoyed with you -
then slowly make him notice you, charm him and make him fall for you.
And a then a little bit of extra push when he's already very comfortable with you and least expects it and is incapable of saying no anymore - because he's charmed and you're already sitting (riding) on top of him.
Seira was actually playing the same long game, but then felt pressured for time (saw competitors) and just wildly overplayed her hand. She moved too fast and too creepily and aggressively...
What happened to Seira is exactly why other girls play it "very safe", except for Yuka, Yuka is a player and she scored and executed her strategy to perfection.