<human>: Can you provide a brief rundown of the text in within 3 sentences?

Just need some advice. 

My boyfriend has  a friend (who he briefly dated for 3 months 4 years ago who lives far away) and he covers up their communication. She lives far away, she is friends of friends, and honestly, I don't have a problem with it. Except that he is covering up their innocent conversations. 

On his phone, he has her name under "Boss Lady". The texts are innocent, not even flirty, just like funny anecdotes that you would text to a friend. 

a)I know I violated his trust by looking at his phone, but I saw him texting her while we were out. I saw the name Boss Lady, it was late, it was suspicious, so I looked. I know I should of asked. 

b)I don't know how to talk about this without making him feel defensive (I did go through his phone and that is a violation of trust).

c)They hardly ever see each other, she lives far away, he has assured me nothing is going on. 
BUT
d)I don't have a problem with their friendship and I don't know why he would feel the need to lie/cover it up. How do I talk to him about this without having it explode?
<bot>: Boyfriend has a lady friend with a strange name in his phone and innocently texts her friendly anecdotes, but covers it up.