You could take about the pronoun "you" to show how Gerald is in control, and he has chosen the ring, and that Sheila is aware that she has little say.
Also, you could take about how it is the ring that he "wanted" her to have which further conveys Gerald as the dominant partner in the relationship.
You could then link this to how women were seen as subservient during the setting of the play, and how it reflects the society of the time.Context is not something that you get marks for but you could refer to Priestley's views about equality between men and women.
The words 'you wanted' implies that not only is Gerald in control of their relationship, but he also controls Sheila's mindset. The fact that she poses a question connotes to the reader that she adheres to not only Gerald's preferences, but also her outlook on life, and the way in which the ruling class should conduct themselves within society.The word 'wanted' creates a sense of ownership and entitlement- it is almost as though he has a right to make Sheila's decisions for her, as her husband to be.
This has been done intentionally by Priestley to represent the way in which women were treated during Edwardian England- their sole purpose was to merely support their husbands, but never by necessarily offering their own opinions or advice. This is why Sybil recognises that they must exit the dining room and 'leave the men' to discuss matters of importance.
The fact that Gerald now has the ability to make decisions for Sheila perhaps implies that she has become nothing more than a possession that Gerald is free to manipulate as he pleases.The fact that Gerald chose the 'ring' is equally symbolic of his dominance within the relationship. A ring is a symbol of not only love, but a covenant between two parties- it is supposed to be be emblematic of a mutual agreement between two people.
Conversely, since Gerald had the final say on which ring he presents to Sheila as a supposed token of their love, this implies that their relationship isn't reciprocal in nature, but is in fact controlled entirely by Gerald.Again, this has been done by Priestley to show the lack of gender equality at the time the play is set. Gerald and Sheila are both members of the ruling class, yet Gerald is perceived as the more dominant member of the relationship simply because he is a man.
Priestley aims to teach the reader an important lesson about equality- irrespective of whether you're a woman, you are free to make decisions for yourself, without the fear of being coerced by the opposite sex into fulfilling their wishes instead of your own.