There is quite a bit of disconnect in this game between the story and the sexual content, which is rather disappointing. I find it really unbelievable that the MC would try to fool around with basically ALL the girls in his team when he has so much to lose if the team breaks down because of jealously and cat fights between the girls.
This completely breaks my suspension of disbelief. I don't see the MC fooling around with the girls and the MC trying to form a team and win a tournament as the same character. Because they are radically different and their motivations don't align at all. In fact the mc in the sexual content doesn't have much of a personality at all, he doesn't have any reason for what he does, he doesn't think about the consequences, that he is literally betraying the girls. He is just a blank slate for a player.
This is a very serious flaw in an otherwise fantastic game. I shudder to think about the future implementation of harem in this game - it might just turn me away from this game.
If it turns you away, then good riddance.
Nah but on a serious note, in this game you play as the definition of a virgin. MC has been obsessed with volleyball his entire life and he haven't had the time or need for any sexual activity. After his encounter with Lexi and feeling a completely different kind of bliss than just him jerking himself off, it would make sense why he actually got into that mindset that he just craves that bliss again and pleasuring other people. After his moment with Eve he really loved the noises that Eve made and that she loved when he touched her. So he literally studied up on it by visiting porn sites so he could actually learn how to pleasure a woman.
Short summary: MC has only had his mind on volleyball and training to win. He turned away every single girl and opportunity that he had. He is quite literally new to all of this new kind of bliss that he is experiencing with these girls that he's going to coach.
I will say that you are wrong about that their motivation doesn't align at all.
Eve actually wants to play volleyball and has been craving to be on a team since highschool. MC started training her and she is improving alot.
Zoe is following her hero's footsteps (the mc) and wants to become the greatest setter and MC will teach her everything he knows.
Saki is picking up volleyball again because she is doing purely for the MC.
Lexi doesn't care about volleyball but she will join if MC makes it funner to play volleyball than to party all day n nite
I'd say that their motivation is about MC and ofcourse they have history with volleyball in one way or another.
Fiona probably loves volleyball but she probably got into the wrong crowd and everything got messed up there.