When his ACTIONS match his WORDS, then you can *start* to trust him. Until then, you have a lazy alcoholic/drug addict sucking the life right out of you, not to mention putting your very own sobriety at risk.
I take it he thinks you'll cover his share of the bills or does he think a Fairy will drop from the sky and pay the landlord so he can go out and get all drunk and coked up?