How long have you been married?
How old are the two of you?
What makes you think he might be cheating?
Has he ever cheated before?
Thank you for that info Mamo, what did you do when he cheated on you the other two times?
What is his excuse when he comes home late?
Why did you stay with him after he cheated the other times?
He doesn't want to tell you where he is when he comes home late? and your married?
Different people deal with things in different ways. I'm not sure why you would be married to someone who comes and goes as they please without telling you where they are going and what they are doing. If he has cheated on you before then he should want you to know where he is and what he's doing if he loves you and if he's not cheating.
The botXXXXX XXXXXne is 'we teach people how to treat us', the first time he cheated on you and you let it slide, then he realized that it was ok to cheat on you. When he cheated on you the second time, again he realized he could do it and you wouldn't leave. The best indicator of future behavior is past behavior and if he has cheated on you in the past then chances are good that he will cheat on you again, if he's not cheating already. If he is hanging out late, and not telling you where he is or what he's doing then it's a good chance he is cheating again.
The only way you can find out is to hire someone to follow him and find out, or to do a little detective work yourself. Check his pockets and phone, follow him when he leaves. You have to stoop to all of this because he's not willing to be honest with you. You should think about putting your foot down and demanding to know where he is, and if he still won't come clean with you, consider leaving, rather than have someone treat you this way.
I welcome your thoughts, let me know if you want to talk more