Actually curious: Has there ever been a school council vice-president in the history of the yuri genre who wasn't at the very least crushing on the (current, former) president? Cannot think of any off the top of my head. :-/
Pretty sure it's a requirmement stipulated for postulating to that position. I remember a couple of years ago a small group of activisits in Japan were complaining about this discriminatory practice against heterosexual students that wanted to become the vice-president.
There's plenty of shoujo, and probably shounen too, where a hetero guy is the vice-president and crushes on the president. So, the requirement is ironclad, but does not seem to have gender orientation sub-requirements.