I don’t think anyone is stating otherwise. But don’t you think others might? I’ve seen many situations in which romance started between two working individuals at work. I think it’s within human nature to get involved in a sexual relation, not because each individual is in need for that, like you’ve stated yourself, but because if the situation presents itself it simply might (again not always) trickers that need.
Simply put, yes, a working contract most often doesn’t involve getting into relationship with your co-workers or clients, unless you work in the red light district down here in Amsterdam the Netherlands where I live, but humans do have emotions, once a person trickers these emotions, one way or the other, people could simply fall in love or feel sexual attracted.
It’s, imho, not about being good or wrong here, these things simply happens within the context of being human. It’s only bad when it occurs in ways which are ethical wrong, for example when one person is using his or her status at work to suppress another co-worker in search for sexual conduct. Then you’re talking about abuse.