it is sure hard to tell at this point, he may be telling the truth or not. just wait a while then check again later to see if he is still looking at the same sites- also you can check the recent documents area and history on the computer, but beware sometimes that idea can backfire it is kind of sneeky but so is what he is doing. not saying that 2 wrongs make a right but it is a precaution towards the idea of being cheated on.