Mistreating horses

I was, of course, disgusted by the train-crossing scene, where Gerald furiously whips and spurs his horse; I was appalled when Gudrun subsequently had sex with him; and I was a little disappointed that Ursula would continue to socialize with him. I decided that this was supposed to be character development, that the movie was indicating that we should not like these people. That's fine. I don't.

But then there is a scene in Zermatt where the German artist shows the two sisters a painting of a man on a horse, and he says he had to slap the horse really hard several times to make it pose correctly. The sisters act as if this makes them uncomfortable. I don’t approve of his slapping the horse either, but it is not nearly as cruel as what Gerald did. So I don’t understand why that bothered them when they obviously were not too particular about Gerald’s behavior.

Finally, people don’t just put stuff in a movie at random. If there are two references to mistreating horses in one movie, there must be some connection we are supposed to make. The only one I can think of is that Gudrun is apparently going to have sex with the German artist too.

Is that the point? Gudrun is turned on by men who are cruel to horses?