Is he talkin to another girl???

I have been with my boyfriend for about 4 months now and we live together. I have cut off all ties with x boyfriend’s and guy friends..(stopped txtn and callin frequently) you know..out of respect for him and our relationship! So one day I was curious and went through his txt messages..(low I know) but I found out that he was talking to this girl named na’shea and he was telling her how he wanted to hear her voice and such!! And that really hurt me and I confronted him and he told the truth and said he was sorry!! So I forgave him! Then his ex girlfriend still calls everynow and again as well as other girls..and I’ve asked him many of times to tell them to stop callin and txtn him and he just says that he does and they still do it anyway or that they just call every blue moon!! And so this has become a problem in our relationship!! and now he erases his call logs and all his txt messages…and im like why would you do that if you didnt have anything to hide…because im always leaving my phone around and he can see whatever he wants..because I have nuthin to hide…is he talking to another girl do you think???