How about this for the moral: When X is forced to love Y by external circumstances, and Y knows it, then Y's feelings towards X will be changed TOWARD creepy and AWAY from reciprocation.
I think this was covered by the story, actually. Remember, this wasn't a change that just affected Christian, it affected everyone. And some (Pete, sock-puppet boy) were affected much worse. The story was, to a large extent, about how Lilian came to terms with
everything changing. And once she accepted that everything changed, and decided to live in the new world, she just had to treat it as it was, without reference to what came before it.
I don't see why she should be able to accept magic changing Pete into a vampire as a fact about the world but still see Christian as being under coercion. If the spell was temporary, or cancellable, I would agree with you.
Put it differently - if I hold a gun to you and tell you that you must blindfold yourself and learn braille until you can read fluently in it, then I am coercing you. However, if you are involved in an accident and permanently lose your eyesight, and I teach you braille, you are not being forced to do anything; circumstances changed irrevocably, and you are adjusting. I think that, regardless of whether Lilian and Christian were a good match or not, it is not correct to treat him as if he was being forced to do anything.