wills I agree with your observations. There's poignancy to the story. Yvonne has given everything she has to life-she's brought up kids, she's achieved highly, she's built a marriage to a faithless husband. She's done everything expected of her. Why shouldn't she have sex in a broom cupboard with a mysterious stranger? Why shouldn't she have a bit of fun for a change? Who's it harming?
If Yvonne were a bloke her actions would be written off as a mid-life crisis. If she were a young woman we'd be saying "good for her-go girl!".
Why is it different if a subject is middle aged and female, with a jelly belly?