She did in one discussion about kinks explain that she has a jealousy kink and gets off on seeing the MC upset, which I think does create an issue, but... she also said she did not have an extreme need for this kink and could live without it, so who knows...
I think she downplayed this kink a lot, take the Damian cucking for example, a big part of what got wrong was because of this kink, to the point that any kind of "teaching lesson" was abandoned just to feed this jealousy kink. So yeah...definetly downplayed it.
And about the cuckquean or Lacey sharing the MC with others, as far as we know, both Mia and Anna are already included. The whole thing has various layers, sure, its so MC experiences a "wild youth" as Lacey did, but its also a compensation to Lacey screw ups and a way to give a reward to the rest of the girls. Lacey can be a lot of things, but she is good at manipulating people into seeing only one part of the whole.
For MC sharing Lacey with other dudes, well his possiveness should prevent that, but Lacey has this trait that allows her to twist things, if you look at the conversation where the jealosy date is proposed, its in fact Lacey who leads and guides the whole thing and makes MC believe it was his idea. So, in theory no more Lacey with other dudes, more so if she continues to realize how bad she treated MC and how damaged he got because of her, but anything is possible.
I think some of the other characters are going to step into the "oops, I screwed up" role for a bit, but how... I am unsure.
Anna is the one with all the warning flaring up. She is left behind, probably be targeted by the villains, has this change of attitude, and really after all the damage Lacey caused to MC her relationship with Lacey should be gone. If she really loves MC and wants to protect him (doubtfull or it would have happened already) or thinks that she is not really trated fairly in the sharing plan, i can see her stepping into a "Mia role" and be the one causing trouble for Lacey and MC. Of course with similar intentions to Mia (Replace Lacey, or at least get more attention from MC)
Lacey is VERY jealous, she doesn't take it very well at all and even in small things such as learning about Christine as his intern, she was overly upset about it when she first heard about it.
Just remember her attitude during MC free pass. If its with Anna she was okay, and even tried to direct MC to Mia. But Christine or Kelly, damn. Which its really contradictory. For a girl with sex means nothing emotional, she is "okay" with him fucking girls that are in love with him and who he holds some love for, meanwhile girls with barely any feelings cause her jealousy. Wouldnt be it better for her supposed teachings if he fucked girls with no feelings or attachements?
As it is now, she knows it hurt him, she understands it from an analytical view, but not a true empathetic one of the damage she has caused.
Completely agree on that. She deserves some harsh bereating that leaves her fully understanding the damage she (and the rest) caused to the MC. Not just know, but undestand. That would fully start her redemption, so far even with the therapy sesions its just pretty words, because she isnt acting on this supossed regret, she knew the jealosy date was "super unhealthy" and yet she did go along with it.
And yes, a lot of her regrets and repentance so far have being tried to be resolved by dragging the MC to her level instead of her stepping up and doing better. In fact even the sharing plan is part of this, instead of her changing for the better, she is forcing a change in him to accept her as she is.
So far, Lacey is the only one that has expressed the desire to change, to accept that she screwed up, to accept how hurtfull and damaging she is to the MC and wants to do and be better, but at this point in the story she hasnt really acted on that yet. But hey, compared to some of the others (Mia for example) at least she is aware, at least rationally.