To know no bounds means to be without limit or restriction, but in this context the speaker's passion is very restricted
Consider the staetement "Well, your passion certainly seems to be very restricted and limited, she smiled, kissing him, but you must admit its strange.". Based on this statement, is "Well, your passion certainly seems to know no bounds, she smiled, kissing him, but you must admit its strange." a true statement? Yes/no/unknown