Exactly this. One of my exes accidentally killed my dog years ago. She left a bunch of grapes out on a low table while I was out of town, and the dog ate them. She didn't realize grapes can be toxic so didn't think anything of it, until my dog started being very lethargic. She took him to the vet but it was too late.

I'm not going to lie, I was really pissed and very unfair to her when I first found out, but we got past it. I lashed out due to grief and surprise but then realized that she was doing her best and she went to an emergency vet as soon as she realized something was wrong. We stayed together for about a year after that and broke up for unrelated reasons.

I would have absolutely broken up with her if she had lied to me or hadn't sought veterinary care, though. And even if you think the cat is dead, it's a good idea to follow up, even if only to put your wife's mind at ease. But it can also be surprisingly difficult to determine if an animal is alive in some situations. I have a little more experience here than most (have worked as a vet tech, have a lot of emergency veterinary training due to having working dogs) and even I have a 14-year-old dog who I have sometimes thought died during the night because she breathes so shallowly sometimes that you can't see it, and you can shake her like crazy and she still takes awhile to wake up. Once I was 100% sure she was dead and just left her alone while I tended to my other dogs, planning on getting her and burying her once they were all calmed down. I started giving them their breakfast and suddenly heard her howling in the bedroom because I'd closed the door and she heard me feeding them and was very upset about the prospect of skipping breakfast. My husband and I joke that if she does die during the night, we'll wait for rigor mortis to set in before we bury her just to be sure. So yeah, better safe than sorry, especially when you are the accidental cause of death and trying to keep your wife from blaming you for it.