You should use `form_id` as theme key in `hook_theme()`, which is `user_profile_form` in the case.

```php
function MYTHEME_theme(&$existing, $type, $theme, $path) {
  return array(
    'user_profile_form' => array(
      // …
    ),
  );
}
```
See [Theme Profile2 Form][1], a support request opened for the Profile2 module.








  [1]: https://www.drupal.org/node/1895210