<human>: Can you succinctly summarize the text in 1-3 sentences?

So I have a girlfriend who at no point has any prejudices against me masturbating, but today when I was browsing through the internet I found a five second gif of a sight that although I cannot be positive it her looks awfully like her. The shot never shows the whole face otherwise this question would be cut and dry. I want to confront her about it because it is eating me up inside. 

I have never had any inkling that she has been unfaithful but now my confidence is shattered. The aspects of the clip make me think it was something recent. I worry that if I ask:

1) she will be offended I would even consider her possible of that

2) it is her and she doges or lies about the situation 

3) this damages trust between us even if it isn't her

What would you do in this situation?
<bot>: looking to jerk it, come across gif of what may or may not be my girlfriend, is it even acceptable to bring it up to her?