"you can be totally trustworthy in the realm of business, yet not in romance."
If you can't adhere to the terms of a voluntarily-entered personal contract with a person to whom you've promised utter faithfulness, why should I believe you'll be trustworthy with regard to some boring, impersonal business contracts?
It's perfectly possible to be trustworthy in one thing and not the other. If you can't trust a lion with your flock of sheep doesn't mean you can't trust it with a bunch of bananas.