Her freedom is not your's to give or take.
You need to let her go, you cannot stop her. Don't be needy, that will only make things worse. Remember, a woman will not have intentions of sleeping around. You piss her off, she will be taking the entire football team and thinking about you telling her not to go.
Remember as she leaves, you need to be more confident than any guy who will try hitting on her. Don't text her, don't call. If she calls/texts you from a party its a good sign. If she asks why you never contacted her, let her know you wanted her to have some fun.
EDIT: look at it this way, man. If you fall in love and marry her and sail off into the sunset with a hot trophy wife, nobody will know she had a fling at a college party. You still have a hot trophy wife.