<human>: Provide a brief overview of the text.

Alright, so I was using his phone to look something up, I went to close all of the applications open, and see a photo of a girl I know completely naked out of the shower. I was heart broken. Asked him what it was, how it got there ect. He said it was an old photo he found in his email and that he did masturbate to it. He does have a little history with this girl from over 5 years ago. 

What does this mean? Is it a form of emotional cheating? Does this mean he isn't happy with me, my body, our relationship? We have a very active sex life and he says he is completely happy with our relationship, but its hard to believe that knowing that he needed to jerk off to someone else. I cant help but feel self concious now and insecure. 

We talked about it and he says it means nothing.. he wasnt thinking, but I cant get over it. I feel like there has to be a reason.

Im not sure what the next step is. How can I trust him again?
<bot>: Boyfriend admitted to jerking off to a girl I know, with old pictures he had. Not sure what to think, need some advice or perspectives.