Uggs, this is the crap I hate off people, when confronted they make the decision to outright lie to a person who loves them. If you recalled his dating site profiles you could bust him on making up a fake one and hitting him up, see what he says back to you on that profile, that would be definite proof he is on a pu$$yhunt. I think he should just be honest but he won't because he wants those sites and you too. He wants it all. Let him know he can't have it all, that isn't how a committed relationship works.
“The one you love and the one who loves you are never, ever the same person.”