Do you think he cheated?

My old boy had a hickie on his neck, I questioned him about it and he says some girl was kissing on him and then he told her to stop and claims that he got mad when she did it but my thing is do you think because of the hickie that he had with the girl? SN: for the most part in the relationship he has told me his whereabouts, has called almost everyday, all day, when he gets off work, etcetera, etcetera so im not really sure if he is telling the truth about the situation. Help. I dont want to falsely accuse and at the same time i dont want to like the dumb *** girlfriend who doesn't know whats going on. Please serious answers and opinion. NO BULLSHXT!