For the models it is still only a business relationship, except in very rare cases. By the same token, prostitution can also be a meaningful personal relationship, as shown in the movie Pretty Woman.
I mean, a friend of mine was an escort, and certainly ended up in entanglements like that. At the end of the day you are two human beings. Whatever your professional situation, these things are inexorable.
As your sibling commented mentioned, even if they attempt to treat it as a business relationship, not all people can handle it. The mental toll of receiving affection and then basically fake reciprocating it is hard, and not everybody can take it.