I thought about that the other day during the hearing when word came out about her unusual response to not finding Cooper at daycare. I suspect RH has either left Cooper in the car for brief periods of time and she was the one who was not happy to hear know it and therefore shoved research in his face at home about how very dangerous that practice is.
I think Cooper was the glue being used to keep RH in this marriage after his alleged affair a while back. I think RH took that idea and his wheels started turning. A way to be child free, a way to make it pay, and still come out the sympathetic victim of a tragedy.
of course, if the "what time are you picking up my buddy" text was real, and happened, and it referred to Cooper, then by her arrival at daycare, LH already knew RH indicated the child was at daycare and she was expected to pick him up. So given that, maybe her reaction was normal and expectable.