Don’t confuse age of consent with consent. If, well actually when, it goes pear shaped who knows what will happen. The girl, if twisted, can file a complaint that he raped her (not giving consent). He will be behind the 8 ball at the start and will be better off paying her and the police to make it go away. Tell him to think with the other head. Other than sex what else can a 40 year old get out of an 18 year old uneducated Thai girl? Dumb guy.