Um... no not "because she's a woman". That's just misogynist BS
There are plenty of authors who can write about the other sex quite effectively and convincingly. There are also authors who can't write effectively no matter what sex any of the characters are.
The author simply either intended to drag it out for much longer or simply lacked the skills to converge the series. It is just that the book sales dropped faster than expected and the publisher pulled the plug (leaving her with an epilog as the only graceful exit). I've read some of her other work... .she's really pretty good at specific scenes or character design (of either sex) - she just doesn't seem to have a lot of skill points in telling a story that builds to a climax and then ends satisfactorily.