The reality of the world, sad to say. No matter how we associate money with evil and greed, we have to agree that no one can live without any. At least, I am talking about normal, average people. Some can live with a little, some would desire more. It fuels your life style. The more you have, the more you can burn and get a better ride in life. Greed and love for money can be a good motivation if use in moderation. It helps a person to progress and work hard to attain that little extra everytime. It starts to turn bad if it becomes uncontrollable, when a person will do anything with any means to obtain the riches. But again, in reality, most of us judge a person by how deep his/her pocket is.
In my line of work, I got to travel to neighbouring countries and China. I do notice that many of the rich men in those countries have mistresses - beautiful, slim and tall. Some could even take part in supermodel contests. It's such a common phenomenon that no one will feel unusual. There are plenty of gossips of who slept with whom to get to top, etc. Hm, make for good lunch time and drink topics at times.
Actually, do not think any one here can help besides giving our 2 cents worth. Do not even think our opinions will help in any way. We do not know her exact situation. For assumption, we can only guess that she needs the work to pay for her tuition fees and she would have to entertain clients unwillingly. Not many options - either quit and find another job or continue but draw the line very clearly on entertaining. But at 19yo, I am afraid she would be swayed into the "dark side" if she interact with her boss and the clients too much. The lure of easy money is sometime too difficult to resist.