Still Life by Isobel Hart

A woman must discover the meaning behind a new virus affecting men before there are too many infected for them to be stopped.
When Samantha Davis and her boyfriend are involved in an accident, on the same day a new virus is identified, his recovery appears to be a miracle. Until he turns on her.
Determined to understand the changes in him, Sam joins with others to uncover more about the virus. But the knowledge they gather poses a threat. The infected men want to stop them. And soon.
Resolving to meet the threat head-on, Sam prepares for the toughest fight of her life but finds herself caught between two worlds; still caring for the man she once loved, as her affections grow for another, while fearing for her life and the lives of all women. As the net closes in on her, she must decide whose life is more important.