Not sure whether my MC is being raped or not?

In my new YA novel, my 16 year old MC,Lena, works part time in as a ranch assistant. She secretly likes to smoke a little pot sometimes and has a bit of a gambling problem (not a drug addict). Anyway, her boss, a sleazy 45 year old man, knows her secrets and threatens to tell her strict parents the truth. The only way he'll keep quiet is if Lena has sex with him everyday at work. She doesn't want to do this and feels repulsed by the entire situation but agrees to do it.

Is it rape if he's not physically pinning her down and attacking her? This is important because a social worker gets involved and I need the correct terms.

Thanks.