Recap: Dionysus is the god of wine and parties. He's all over Greek myths, but in the story of King Midas, he's the wish-granter. Spoiler alert: it doesn't end well.
Dionysus doesn't get a ton of screen time during this story. In fact, the only time we really see him doing his thing is when he grants Midas's wish. But Ovid includes a pretty important detail when the wish-granting goes down. According to the Roman poet, Dionysus is "sorry that [Midas] had not chosen better."
That's right: Dionysus knows that Midas has made a bad choice, but he grants the wish anyway. Why? Well, it might simply be a matter of keeping his word. Dionysus promised to grant any wish—he never said that it had to be a smart wish. Or maybe Dionysus wants Midas to experience the consequences of his decision. After all, one of the story's major themes is that greed has consequences. Ovid's text doesn't really provide much evidence for us, but chewing on it a bit might be central to deciding how we feel about the story.
For much, much more about Dionysus, check out his profile on Shmoop.