For the dev:
A lot of the netorare kink in particular centers on the feeling of loss/control and the ensuing jealousy. Currently, Diane is someone that is inherently very slutty - this makes it difficult to see the relationship as anything special, and takes away from how meaningful the cheating actually is - part of this issue is with the fact that she's just very open with everyone, and there are also very few scenes where she's in a 1on1 with someone else.
I think what would really elevate the netorare would be a main antagonist for girls - for example a specific corrupt enforcer or perhaps the vault trader that is actively trying to corrupt them as you open the vault to more sexuality gaining influence over them. This could also serve as a somewhat simple alternate path to existing content, which could be rebranded as slut content.
Another thing that would be nice is to be able to pick specific people for Diane to seduce, after you tell her you want to be cuckolded by her.
I'm open to answer any questions or elaborate on these points if this particular bit of feedback interests you at all.