First Marah! I LOVE YOUR HUSBAND!!!!!!!!!! It's like he took the words out of my mouth regarding this issue. He sounds like a very good, sweet man. And EVIDENTLY, he is in love with you
The problem with female is it can refer to ANYTHING on this planet that is of the female sex. ANYTHING. By calling women "females" you are intentionally ignoring the fact that they are humans just like you (gy--mean to be men specifically). It's usually men who have a problem with women who do this.
Guys is sex neutral. That is to say, when I call a man a guy, it is still implied that he is a human being. We don't refer to male animals as guys--only humans of the male sex.
Kuddos to your husband, but I knew he would know what's up!