School Days/WMG

Otome's Friends (and possibly Taisuke) won't be in the clear for long

Why? Well, remember how that one girl they bullied (and in the case of Taisuke, raped) snapped in the finale? Yeah. If this troper recalled correctly, there was another show where something like this happened, girl got bullied by both students and her step-sister, she snapped and killed them all. This Troper has the feeling like that is gonna happen to Otome's Friends and possibly Taisuke.

That is, if you know, Kotonoha actually survives being stranded on a boat in the middle of the ocean.
They probably start sleeping around with everyone die of horrible STDs or something.
They'll hear it on the news and become extremely paranoid. The only thing everyone knows besides the murder of Sekai and Makoto is that the murderer is missing. Sure, Kotonoha is in the middle of the ocean on the yacht, but in order for that to be proven as true (someone could have seen it as a lie and say that she's still hiding somewhere) they have to find the boat. The girls will begin to think that Kotonoha is coming for them next and fear for their lives.

The series represents the fantasies, daydreams and personal fiction of Makoto Itou.

Most of the events in the show are but fleeting day dreams of the main character. Considering Makoto is terribly afraid of women at the beginning of the series, plus the Valentines OVA, it seems incredibly fantastical that everything that moves would suddenly become so attracted to him. Why else wouldall the women suddenly love him? Have sex with him? Have three-ways? Murder each other over him?

The starting events really do happen to him, but nothing ever comes of them. He has an awkward relationship with Katsura that strains and breaks under Makoto's inexperience and perverse forwardness.
He's terrified of women and hardly knows what to do around them. How does he become a player all the sudden? Even his fictional self can't explain it. It's why he's always tripped up about his words.
Sekai's surprise kiss at the end of episode 1 as well as the "practice sessions" are all fantasies because he's more comfortable around her. She set him up with Katsura because she's an outgoing person and saw an opportunity. This helps explain why she changes so dramatically when the romance starts; it's not real.
Makoto is probably some sort of writer. He obviously cares little about school work and is a quiet and/or shy guy most of the time. Plus, we never actually see him doing anything for fun (besides women). The story evolves as he fantasizes about his sexual life evolving.
When Makato and Katsura's real life relationship ends, that's when the story goes off the deep end. Every girl suddenly wants him in the fantasies. And the cheating is why he can't be with her. Then he later feels bad about all the cheating his fictional self does, in addition to his failed relationship, and punishes himself by killing himself.
Katsura was a quiet girl to begin with. It's easy to write her later as being crazy. This might in part be his interpretation of her - we do know he never felt quite comfortable with her.It could be part of his anger towards her.

The series is an RPG of School Days...and the PC doesn't care about getting a bad ending.

The whole series is the player-character jerking around the girls: Makoto's fickleness is because the PC keeps switching girls to focus on. The bad ending of the anime is the PC's punishment for not treating the girls well.

Makoto is Bi-Polar

When he finally gets together to Kotonoha, the elation his acomplishement-as well finally losing his virginity- triggers an extreme bout of mania. That drives him to want to experience as much sex as possible. It also result in him beacoming bored with the realtionship stuff if Kotonoha and seek out the other girls. He doesn't consider their feeling because he is to absorbed in his own euphoria and his own heightned sense of self worth, which is also why it is not until Sekai sticks the kitchen knife in his gut that even occours to him that his actions might have consequences.

Makoto is Medium Aware and extremly bored this play through

Makoto knows that he is the male hero of an Eroge and has been though this scenario countless times. He knows excatly what to say to get both Sekai and Kotonoha to fall in with and live Happily Ever After. He knows exactly how to let the other one down easy so that can him go and be happy for the both of them. He knows exactly how to get them both to go along with living with a Tenchi Soloution and even how to get the hearts of the side chars. He may have even tried all of the Gay Options. He is has done everything in the game and is now Jaded. So this time around he goes "Fuck It, this time around I shall be as big as asshole as possible just to see what happens." The result is the School Days anime. The reason why he does not seem to realize that his action might have consequences is because, in his mind, the don't have consequences. No matter what he does, once the scenario has unfolded, the ending credits will play, the game will go back to the title screen, he will select "New Game" and he will will be back on the train, watching Kotonha read her book and start over again. He shall be a nice guy than.