Pets & Vets

hello i have 2 indoor cats, the female was one month old when i got her,now the male is 5 years old) and the female is 2 and the half years old, the female is very aggressive toward the male whenever he is near she hisses and attacks him even when she is not in heat period. I want to know what is better to spay her or not, and if there is anything to be done for her to get along with him. Thank you