I would take this opportunity to explain how important it is for the trust between the two of you to have him honor his word. This means clarifying the current issue with some detail. As an example, your boyfriend might want to text others in messages and not feel he has to report to you on these incidental texts, or you might insist he not text old girlfriends. The gray area between the two on you needs to be discussed and made clear. Use the situation to advance the understanding of your expectations. Couples that evolve in this way are investing in their communication with each other – which is an investment that will be more valuable as time goes on.