My girlfriends vagina smells unbearable, from distance as well she doesnt seem to notice it but it smells like its rotting whats the reason behind this? ive tried telling her about it but the smell continues?

She may have bacterial vaginosis, an overgrowth of mostly normal bacteria. The main symptom is odor, often "fishy" (resulting from the same chemicals produced when fish decay), especially after sex. It can be treated. Have a sensitive and caring discussion with her, including advice to see her gynecologist. (The advice might include no vaginal sex or strictly condom use for a while.) Good luck.