Question about Marriage in the state of PA ?

My boyfriend is still legally married to his wife. He told me that she won't sign the papers and that's why their still married. Its been constantly on my mind as to why she wont sign nd why hes not trying hard enough to get a divorce. everytime I bring his wife up he gets angry because he said there's nothing he can do. I honestly don't believe him and this is one of the reasons I need to walk away. He has kids with her also and pays her cell bill well they are actually on a family plan. I still believe they live together because I never been over his house. There's so many things wrong but I love him and its so hard to walk.away but I know I have too. I mean if a person does not want to sign the divorce papers in the state of PA.does that mean unless the ot her person signs your gonna be married till death ???