Right or wrong, we teachers DO have a morality clause in our contracts. Teachers can be fired -- though they'd get a warning first -- for "living in sin" (though realistically, the administration probably doesn't know where /with whom most of us live) or being drunk and rowdy in public. In the real world, this doesn't happen UNLESS the teacher's also doing a bad job at school and they're looking for a reason to dump him or her.
I remember a couple years ago a just-out-of-college teacher asked me what the principal had meant when he said to her as he handed her the keys to her new classroom, "Remember, this is a small town." I told her he was warning her that students (and parents) would be watching her and talking about her. He was telling her that he liked her, looked forward to having her as a teacher in his school, and he didn't want to have any reason for conflict over her personal life. People hold teachers to a different standard; like it or not, this IS an aspect of teaching.
Furthermore, if the rules in this woman's state are the same as the rules in mine, she was NOT FIRED. The article says she's suspended until the end of the year, and her contract isn't being renewed in August. Since she has only two years' experience, she is not a tenured teacher and can be "let go" without any reason, even if she has been a model employee.
Since she's a high school teacher though, I guarantee you the boys in her class would seek out the movie, and then her effectiveness in the classroom would be gone.