I just feel that maybe she only got to do all the horsey stuff when it suited her husband.
So, yes, she’s had success at it but only when she wasn’t having to be the perfect old-style housewife (dinner parties for his clients, social events to help him climb the ladder etc).
I get the impression he will very much have insisted on being her No. 1 focus, pretty much told her what she had to do, and this may well have eroded her confidence despite being a successful horsewoman (if your success is unpaid and considered ‘a little hobby’ by a successful, high earning husband this can happen).
Maybe I’m projecting a bit, but I can identify with having what seems like the luxury of being a SAHM, when in face it’s soul destroying for much of the time. It can be a gilded cage.