I guess you could consider this a follow up to last weeks post, but less about idols and more about emotions toward them. There might be minor spoilers to Amnesia, so proceed with caution.
When the heroine, of Amnesia, was in the world where she dated Ikki, and even after with Toma as her "boyfriend", we saw some very dangerous actions performed on the heroine in the name of jealousy. These all came from three of Ikki's fans trying to teach her a lesson for ever dating, or even hanging out with "their Ikki", without explicit permission.
Ignored Feelings
With this overprotective and violent nature coming from Ikki's fans, they tend to act on their own accord and as a result, they brush over what Ikki actually wants.
Bringing it back to when our heroine is in the world where she is dating Ikki. The fan club had a set rotation for dating Ikki, every three months they would break it off and a new person got to date him. They are trying to be fair to all the members, but they ended up hurting Ikki with him thinking that no girl wanted to stay with him past the three month mark. Now, as a fan club, that idolizes Ikki, it would be counterintuitive for a them to hurt it's only motivation for gathering together and forming the group. Making it a bit ironic that they think they are protecting their idol, but more or less subduing their own aggressive emotions.
After the heroine moves on to the next world, where she and Toma are "dating", the fans were way more harmful. From trash in her mailbox, to random flower pots from the sky, these fans are way off the jealousy scale. However, the kicker is the heroine isn't even dating Ikki, she just so happened to talk to him one too many times. This kind of overreaction to a simple situation sends a message that Ikki can't meet anyone new, even if you are friends, coworkers, whoever, no one, but these club members allowed.
Destruction
Like many hobbies, sometimes you have to look at yourself and see if you are cause harm to yourself or others. In this instances, the club very much is doing just that, to Ikki and anyone around him, which includes themselves. However, like many things in a story, you can't change them because it makes for a more interesting story. This is more or less for people with a dangerous jealousy, just chill out, to put it simply.