Cats ganging up on other cat

[donxavier10]

We are a four cat household: a 13 month old female and three males, each a month shy of a year old. All four have been fixed. The female I rescued from a storage yard, at 3 months old. The boys are all from the same litter belonging to a rescued mother cat that our friend was fostering.

When we first brought the boys home, as 8 week old kittens, they were absolutely fascinated by our female cat. As they got used to one another the boys seemed to take to her as if she was their mother. They would cuddle and play all day.

Flash forward to two months ago and the boys have gotten bigger. One is bigger than the female while the other two are about her size. Suddenly, she doesn't want to play with them anymore. More often than not she will growl and hiss at them if they try to play with her. If she runs they follow her and they wont leave her alone until she either hides or I chase them off her.

My wife says to leave them alone and let them sort it out. That's hard to do when it's two or three going after her and it's obvious they are stressing her out.

Need any advice you can give. I'm at a loss about what to do.