I am baby sitting my friends crested gecko. It's a male and he is about the length of an index finger, and the width of a thumb. (No tail)

My 7 month old female gecko is about as long as a index finger as well but with a tail. She is as wide as a pinky

I let them crawl around on my bed and i noticed the male was being really aggressive towards my girl. He was pushing his nose into her belly area.
He leaped on her and bit her, my girl scattered away fast as the fat male slowly crawled after her.

I am just wondering if this is mating? or my girl is just to small to be with this male, or my female is actually a male.

I am scared if it is mating that my girls tail will fall off from the male biting.