Male red eared slider fighting with female res slider turtle

 
Male red eared slider fighting with female res slider turtle?
I have 3 res turtles male a female and the third one is to young to tell its sex. they live in a 55g tank the water it full to the top because i have an above basking area. I had the Male for 9 yrs he's about 7 inches. the female is 8 and i had her for about 6 yrs. normally he would try to mate with her be he gets rejected all the time, but recently he started attacking her i've never seen him act like this i separate them it helps 4 a while then their back at it plz help is their anything i can do ?
I think,i'm not really sure but i think they don't like each other