Since my son like's Roberta, I'm going to ask her father if she could accept my son's invitation to the dance.
As long as Roberta feels the same way that shouldn't be an issue.
My son is wonderful! Of course she'll like him!
I know you want your son to have a good time, but that shouldn't cloud your judgment on Roberta's willingness to go with your son. It's up to her if she wants to go with them or not.
I don't care, I'm going to ask her anyway.
Like I said, don't let this cloud your judgment. You should instead have your child approach her and ask her himself.