I'm thinking they're going to say he was about to buy her a car.
Words are cheap, proof please.
I've been married for quite a long time and my husband either forgets completely until he sees my gift for him and then rushes out on the day bringing back flowers and a card and telling me to pick up something "nice" for myself all contrite, or my gift is waiting for me when I wake up, chocolates, card etc and then he goes and gets flowers later so they're fresh. So to say after the fact that he was "about to" tells me that he forgot and had had no plans to do anything special.
As for RS cooking for OP, I never did see OP respond that he would love that, was he even going to see RS that day because her plans didn't seem to indicate that, leaving his gift for him to open on his own, "be there like a bear" for cupcakes at a friends etc.