Female cat not getting along with male cat

Ok so I have a female cat about 3 named Nirvana and I had to bring her to my boyfriend's house for issues at my home. He has an older male cat named Damien who is older about 6 or 8. Now, both cats are really sweet, but the moment I brought her over she hisses at Damien. All he wants is a friend, he follows her around when she's out of the bedroom, but she hisses and paws at him claws out. It's been 2 weeks and she mostly stays in the bedroom with us. I don't understand why they don't get along, she came from a previous owner who had a way older male cat (about 10). Both are spayed and neutered. Does anyone have any ideas or comments on how I can get these two to get along or something I could try? Thanks

I think it's more like she is still getting used to her new home. Even if Damien seems to welcome her, she might feel like a trespasser. Here is a link about cat introductions. http://www.thecatsite.com/a/introducing-cats-to-cats

Hi @JazmyneWeaver

Cats need to be introduced slowly.  It's very difficult to just throw them together and hope for the best.  They each have their own personalities and even though she lived previously with other cats doesn't mean she will get along with the cat right from the start.  Just like humans, cats don't like everyone.  Yet, with time they can learn to get along.  It does take time and some effort.  Here is a video as well as a few other sites.  I suggest you take the process slowly.

http://www.catbehaviorassociates.com/a-simple-little-trick-to-use-during-new-cat-introductions/

http://www.aspca.org/pet-care/virtual-pet-behaviorist/cat-behavior/introducing-your-cat-new-cat

http://jacksongalaxy.com/2010/10/01/cat-to-cat-introductions/

Thank you. It's weird she'll meow by the door like begging to see him but then she runs out and attacks him. She only likes about 2 feet between them And she still hisses.