Omg...are putting a toe into the dark Side? Come on over...we have cookies
No, sorry, not going there, silly goose.
My scenario of that morning has been consistent, and I haven't seen any evidence that convinces me it's (necessarily) wrong (some of it is obviously speculation).
I think RH hadn't been spending a lot of time with Cooper, Leanna wasn't happy about that, RH made plans to go to the movies on the 18th without being straightforward with Leanna, he and Leanna argued about it on the night of the 17th, RH got lost in his texting after Leanna left and was running late to take Cooper to breakfast at daycare, received the email at 8:34 about his 10AM meeting being postponed, decided to take Cooper to CFA rather than to tell LAA (or Leanna) he was running late, responded to random Whispers (as he drove, btw, given the times), the last one being to Ms. X about "escaping."
I think RH was likely feeling resentful about having to account for his time to Leanna and for having to ask her permission before going out to play with friends, and that he responded to that Whisper because it's author was obviously going to be very likely to sympathize with him, and to give him the "permission" to go play Leanna wouldn't.
Last, I think the only reason he mentioned Cooper at all was that his not spending time with Cooper had been the center of his argument with Leanna the night before.
So, yah, here I am spending time with Cooper, but geez, we both need our breaks. In other words, my not spending time with Cooper is OK. It's not about him anyway, (what Ms. X said about her own kids).
Rationalization, self pity, selfishness, pique about Leanna, but none of it about Cooper, much less wanting to kill Cooper.