You can use mobile hacking software, but as a well wisher i would like to say instead of hacking, it is better to talk to her and ask directly ask whats wrong with her.

Hello friends,
I want to spy on my girl friend as her attitude towards me is changing day by day. We are living relationship from last 5 years and now suddenly she wants to leave me. I think that now she is talking to someone else. Every time I call her number and is in waiting. Can anybody suggest me the spy software?