How does Priestly present the relationship between Gerald and Sheila in An Inspector Calls?

Sheila and Gerald are engaged. She is delighted with her "ring," and Gerald seems to be happy with what we can easily perceive as a marriage based on business rather than love. It is apparent from early on in the play that Sheila doesn't trust her future husband (she cites his absence the previous summer), but then again, we have to consider that he has chosen to marry her against his own mother's wishes. Thus, there's a bit more to their relationship than Priestly presents early on.