How should I talk to my boyfriend about being open regarding texting other girls?
My boyfriend Paul and I have been dating for a year and a half now and have been working on our communication lately. The other day, I saw that there were texts on his phone with girl who he used to have a thing with a few years ago. Now I'm not concerned with whether he is interested in her because I trust him and believe he's committed to our relationship/loves and respects me. Ive heard from close friends that she is currently looking for people to hook up with and Im concerned she's coming onto him (she texted him out of nowhere; Im fairly sure they haven't texted in a year or two).
I have no interest in reading their texts I just wish he would have let me know that they had talked. Not sure who first initiated the conversation or any idea of what was said (I didn't read any texts just glanced and saw the name of the girl on messages). My boyfriend has admitted to being oblivious with girls he thought were just friendly in the past but then realized they were looking to cause trouble after other people pointed it out to him.
The only thing that concerned me was he asked me to text his friend off his phone but then quickly said he'd do it and didn't let me even though he was busy at the time (I often text people for him if he's busy; I thought this might be because he didn't want me to see the texts to the girl in his recent texts).
I want it to be clear to him that while I trust his relationships with others I would feel better if he simply told me when an old crush texted him so we don't feel it's a secret. How can I bring this up to him in a non accusatory way?
Also forgot to add, I'm a 19 yo female and he's a 19 yo male.