Honestly, can't believe I am saying this... But I'm gonna side with Zara on this matter because they do have a point.
In terms of overall content alone, scenes and such, Ian and Lena are the biggest sluts around, where as Ivy only has a handful, mainly yuri focused. What might and is "implied" about her happenings is more so under the rank and file of off-screen action. And no one cares about what happens off screen anyways.
The issue however, is that Eva Kiss made out Ivy to be the 'slut' of the game. Dresses slutty, seemingly DTF, fun girl in the bedding department. And yet though, that very much isn't the case. She flirts, teases, has some measure of interest with the guys, but nothing really happens fully. It's only 'mentioned in passing' or 'past actions'. While her relationships and relations with Lena, and by proxy Holly, are determined by the player, I would say she is more of a Nun than Slut at the point. If EK wanted to she could have had Ivy be riding dicks for days, have her brag or tease Lena about what all she did, etc. But that's not the case.
So... Could Ivy's overall character and behavior and mannerisms simply be an act of sorts to stroke her ego of her own views, ala having Lena be casual and Holly awaken her slut streak, or could there be a deeper sider to her that has insecurities and flaws that we have yet to see?