Well seeing as Christine and Arnold are a couple since before the story begins, no such thing as Netorare in this game at all, nor sharing, it's pretty much Netori if anything.
"
Netorare is more than a simple act of infidelity, but the fetishization of jealousy and other negative feelings commonly associated with it."
Arnold isn't "stealing" Christine; that's correct, but if the MC is attached to her then seeing her perform sex acts she otherwise wouldn't on Arnold could instigate a feeling of jealousy. She is submitting and the MC is powerless to stop it. Not arguing the tags should change, I'm just saying the spirit of it as it is understood is present in some form.
Netori is something else, I don't think it qualifies in the same way because Arnold doesn't give shit about Christine. Even with Pan, he's not romantically engaged with her so it's more like you are taking his toy away from him and one upping him. The central idea is how the "victim" feels, so it works more one way than the other because the MC cares.
Either way, like I said, not much here in the way of NTR/sharing content.
