- Why would she need an additional skill for acquiring skills if she's already slaughtering absolutely everyone for skills?
- There is no reason to tell him the truth, could just as easily lie that she fended off the killer before he got there.
- If she wanted to acquire the skill after he leveled it up, would likely be easier with her there to support him (and even pay others to give him skills since she's not just talented but loaded too)
This feels like she was not actively plundering before, and legitimately loved him, and
either accidently self-defensed someone to death with a skill like "moral inversion" and turned herself into a psychopath (assuming plunder only/automatically works on death), or was targeted by someone with a skill like possession or mind control.