Haven’t tested it myself, but something like this usually is easier on the brain…
<a href="<?php echo loggedin_user->domain . $bp->friends->slug . '/remove-friend/' . $potential_friend_id, 'friends_remove_friend' ) ?>" title="<?php _e('Cancel Friendship', 'buddypress') ?>" id="friend-<?php echo $potential_friend_id ?>" rel="remove" class="confirm remove"><?php _e('Disconnect', 'buddypress') ?></a>
It’s also possible that because this specific link has ajax attached to it, that it’s returning false before the additional JS message can fire on the click. In that case we’ll need to try a different route.