Actually, Disney planned that she would do something to prince

Interesthing I didn't know that.

^Yeah, he was supposed to be captured and imprisoned by the Queen and later escapes to save Snow White. But it was said that he was hard to animate so they removed it.

yep and as a result they recycled the idea for Sleeping Beauty where Maleficent capture Prince Phillip.

Yeah, but my impression without those scenes is that she is thinking about killing snow white.

All the people above me already answered your question!

I think it was more jealousy

I always assumed she was jealous...

Well I didn't know that chesire.

I think she is jealous. She must be thinking: He was supposed to serenade to ME, not to that little scullery.

I agree, I got the impression she was so disgusted with jealousy she was going to do something about it. Which she does. In the next scene. She decides to have Snow White killed so no one can admire the little princess over her.

Interestingly, earlier story drafts would have had the Evil Queen kidnap and imprison the Prince as Maleficent does to Philip in Sleeping Beauty. She would have tried to keep him away from Snow White so he couldn't wake her with true love's kiss and then he would have had to fight his way out as Philip does in Maleficent fortress (though without good fairy assistance), but a number of budget and animation limitations (including staff not being able to animate human men very well) caused them to scrap the idea. Instead, the Evil Queen just laughs it off by figuring the dwarves would "bury her alive."