Shipping the Phantom & Christine is one of the biggest controversies in the Phandom. A majority of phans support the Phantom & Christine as a couple while a minority support Raoul & Christine as a couple, often citing the fact that Raoul & Christine's relationship is healthy while the Phantom & Christine's relationship is not so healthy. Even I recognize that the Phantom & Christine's relationship is toxic and abusive while Christine and Raoul's relationship is way more healthy.
Some abuse survivors who are still in the Phandom and who were once Phantom x Christine supporters not only stopped shipping the Phantom and Christine but make their fellow phans aware that even if you're writing fanfiction in which the Phantom and Christine's relationship is healthy or becomes healthy at some point in the story, it's still abuse. Some also express that if you ship the Phantom & Christine even in a healthy way by reading and writing fanfiction in which their relationship is healthy or becomes healthy at some point in the story, you support or condone abuse.
I completely disagree with that. If you are reading and writing Phantom of the Opera fanfiction in which their relationship is a healthy one or it becomes a healthy one at some point in the story, it ceases to be abuse. Shipping the Phantom & Christine by reading and writing fanfiction in which their relationship is a healthy one or it becomes a healthy one at some point is not supporting or condoning abuse.
Some of these abuse survivors hold the point of view that just because it's fiction doesn't mean it's any less harmful.
But you know what? The original Phantom of the Opera story was published in 1910, peeps. Unfortunately, abusive relationships have been around way before that. Since the dawn of time, in fact.
I understand how stories like Phantom are dangerous and harmful in their romanticization of abusive and toxic relationships. However, I even though I ship the Phantom & Christine, read and write fanfiction in which their relationship is healthy or it becomes healthy, I call out the Phantom's behavior and actions for what they are: abusive, toxic, and unacceptable.
I do not write fanfictions that romanticize the concept "fear can turn to love" while an abusive partner shows no signs of changing or a willingness to change.
In real life, I would not and do not model my relationships after the Phantom and Christine's relationship. My ideal for all of my relationships is where there is absolutely no abuse in the first place. My ideal for all of my relationships is where there is mutual love, affection, and respect. I do not idolize relationships while they are toxic and abusive. I do appreciate the positive elements of Christine and the Phantom's relationship, but not the toxic and abusive elements.
So my answer to the question in the title of this entry: Yes, it is perfectly OK to ship the Phantom & Christine as long as you ship them in a healthy way by reading and writing fanfiction in which their relationship is a healthy one or it becomes a healthy one at some point.
Reading and writing fanfiction like that is harmless.
However, I am not saying you can't read and write Eristine fanfiction in which their relationship is toxic and abusive. I just don't recommend it.