Is my girlfriend cheating on me?

I have been in a relationship with this girl for a year and a half. However, recently events have evolved which make suspect that she could be seeing someone else. First, she suggested to me that we should stop having , arguing that it should not be the main bonding factor of our relationship. We indeed effected her suggestion but this forced me to check her mobile phone and i realized that there were new male entrants in her contacts whom she was so much in touch with. When i asked her about it, she told me those were friends whom she could not fall in love with, but she was unhappy because of the rudeness in my tone.Later, she begun deleting all calls she makes and the messages. Always whenever i confront her over such issues, she is not detailed in her explanation, and she appears not comfortable with the fact that i doubt her. She simply tells me in a calm manner that if she really wanted to cheat on me she would do so, but she does not want. However, she still cares for me like she used to and she abandoned her suggestion of not having oftenly (we oftenly have like we used to before she suggested so) . She likes flirting with me in public. But the fact that she deletes her calls and messages from her mobile phone has left me with a lot of doubt. And i would not wish to live in doubtful relationship. So, could she be cheating on me so that i should live her or its me who is paranoia.