And when he grows up, he will become one of Siegmund Freud's patients. The timeline seems fitting, too.
The musical was written to show what Phangirls
The musical was actually designed to show why
the Phantom and Christine can't be together and why it would be disastrous, and that the only way they would be together is if everyone was derailed and way out of character.
Remember what their get-rich-quick scheme was? Oversell shares in a Broadway show by a wide margin, then delibrately produce a horrific flop, thus leaving them free to leave the country with the remainder of the massive initial investment without having to pay taxes. Hmmmm...
This was written to spite phangirls and Sarah Brightman
Andrew Lloyd Webber was bitter about his divorce and was tired of all the fan mail and complaints on why Erik and Christine can't be together that he found a novel where Christine died and turned it into the musical for his own satisfaction.
This is all happening in the phantom's head
You know how everyone seems to think that Christine dumped the phantom because he was deformed and not because he was crazy? Well, in the first musical, the only character who actually seems to think that is, wait for it... the phantom. Also, he's rich, successful, everyone loves him, except for Raoul who is inexplicacly terrible because he hates Raoul. The reason Christine dies is because he's more aware of her not being real than the others, so his mind writes her out
- Christine is also both the main reason for Erik's fantasy and the primary reason why his fantasy world can't truly satisfy him, as her presence reminds Erik that the real Christine rejected him. Having fantasy-Christine die tragically after professing her undying love for Erik plays into his fantasy of being chosen above all others, including "Christine's" own child, while conveniently removing the undertones of a reality where he wasn't chosen. There's also Gustave, who's "proof" of Erik and Christine's eternal love while having (presumably) no basis in reality that might ruin Erik's fantasy.