he has to face up to life one day no matter what his circumstances are. he has no-one yet he met you, so he will meet someone else. tell him, i dont think you need to be a bitch but sometimes that helps if he wont take you seriously.
you cannot, not finish with someone incase they do something stupid, that will occurr later in the relationship without a doubt if they are that way inclined.
may take time but be firm and if it is what you need, do not get pulled back in sympathy....good luck