See when he was using his phone
Your partner's phone is a treasure trove of information, and as it collects other key data about their lives and habits, it tells of their possible indiscretion. Look out for these major behaviours that indicate that something might happen.
Track your partner phone number calls etc
If you think you are cheated in a relationship always track your partner or bf phone number. Check who call him? How much time he spends on calls. Also, check if he goes outside to check the phone.
Sometimes it was hard to track your bf phone number, in this situation you can use any phone number tracking website or apps like TruthRelations they specialised in Spy Your Spouse and phone tracking and help you to find a cheater.
Check his social profile:
Social media is also a good option to check what's going on in your bf life. Always check your bf chat section. Also, check the hidden chat option.
Check BF Email on dating sites
Always track your BF email id or computer history. Is he is on any dating site? Or chat secretly with someone you can check using computer history.
But if your panter deletes all browsing history or uses private browsing then it was hard for you to check what's going one. But I have a solution to this problem, you can use reverse email lookup services. Some website track email even from dating sites.
Hope these above-given solutions work for you. Please share your thought in the comment section and ask any questions if any in your mind.