My husband's secretary is making advances on him?

Whenever she calls him with issues from work he goes to his study to talk away from me. Also when I am with him at a company barbecue or event she is always touching him and laughing and joking with him. She joined his company straight out of college and is one of those stupid perky blondes. I believe the skank is making advances on my husband because he is her boss. How do I get her away from him?