Is it ok to date my karate student?

I'm 25 and teach karate. I had around 30 students rangeing in ages and I love teaching it. One of my students is called Ashley and is 21. She's really beautiful and I really like her. She's been giving me obvious signs that she likes me like asking me to show her moves and grab her in grappling positions. She contastly says how handsome and strong I look and her friends keep telling me that she wants me. I really like her and would date her but is there like a law or rule on dating a student?