Errrrm....Id say he is definatly hiding something just because hes deleting the browsing history, but the way you have to think of it is,, it mite be as innocent as just waching porn. Alot of girlfriends have a problem with men watching porn... so they feel the need to hide it, which makes everything they are doing suspisious,,which in turn... turns us into detectives. Id say hes more than likely just browsing porn, dont look too much further into it, and dont end the realtionship over it