This is a joke. It is meant to be funny.
There's a nice boy named Sherman.
There's a not nice girl named Penny.
Penny gets her way by calling Sherman a dog. That's not very nice.
Penny is going to be in a painful wedding.
Sherman wants to save Penny because he is a nice boy, not because he has a crush on her.
Sherman is not in love with Penny.
Sherman rather would spend time with someone who is nice and not mean.
Sherman is a very nice boy and is only friends with Penny.
He holds no romantic feelings toward Penny.
Joke/crack. Don't take this seriously when it was intended to be funny.