They're both responsible. It's probably more her fault than his but still.
Good luck now. One of my friends was in that situation, well he was with the girl for 2 years, then he broke up with her but he kept having sex with her. The girl was crazy, she got pregnant and blackmailed him "we don't get back together, I keep the child". It ended 'well', he cut her out of his life and she aborted.