Boys usually keep teasing because boys don't know how to flirt so they do it to seek girls attention and reaction. This strategy will backfire them though, if the girls feel annoyed by the teasing.
If a boy keep teasing a girl the most, other than any other girls, he definitely thinks she is attractive or she has something that he likes. If the girl begin to feel annoyed, he will feel really regret and apologize (you can notice his sadness and disappointment if he isn't forgiven)
