I don't like that celebrity culture can have such an impact on our politics, but there is no denying that it does. I totally agree with you that she is infinitely more popular and likeable than Trump. At the end of the day, he's supremely jealous that him giving similar endorsements doesn't have the same effect. In fact, there have been candidates he's hurt in recent elections.
I don't doubt he actually hates her, but not simply because he endorsed his Democratic challenger. It eats at him that he'll never reach the level of fame and stardom she's at.