Why do girls do this?

It's simple: her behavior is to get your attention, not to dislike you. . . . . .

Personally, she likes you.

Maybe it's your performance after your confession was rejected, which disappointed other girls; Because she is obviously testing your sincerity. In that case, it will be more sincere!

Or maybe, your confession is not for her sake, but for yourself.

So try to communicate, admit mistakes and clarify problems.