He thinks white lies are ok ???

My boyfriend has been deleting recent text conversations between him and certain guy friends. But will leave other conversations undeleted. I can only imagine he deletes them because he has said something that would upset me. He always lets me use his phone if I want so it would make sense. I jokingly said "I bet you delete text messages" and he lied and said he never does. How can I trust him when he deletes conversations and claims he doesn't? I have had the honesty talk with him SO many times. And he literally said that white lies are ok if he thinks it will save us from an argument or me getting upset. Uh, no. That's not how it works.