Hi Lindsayfan!
well, there seems to be a little confusion as to whether she is really Marat's girlfriend or just a family friend or perhaps a cousin of the Safins as she bears a striking resemblance to Ruasa, Marat's mom. No one knows for sure. Its all speculation at this point.
ayway, here is some more info courtesty of theguyfromrussia.com:
"Ok, Marat arrived at the Australian season with this *lovely* lady and of course, the rumour mill started doing overtime. So who is she? Well she's a Russian called Masha who seems to be a friend, nothing more. However, she does bear a slight resemblance to the Safin's, especially her eyes and eyebrows, so could she be a relative, since most of the Safin clan are in Australia at the moment? From what people have said she seems to have been giving Anatoly and Denis a hard time in the box (sniff sniff!) and some eyewitnesses have said she looked more involved with Denis than Marat! We shall see! Anyhow, if that is the same girl in the black and white photo, then he has known her since 2000 at least!"