Woman's Life (jokes)

What is the difference between girls/woman aged: 8, 18, 28, 38, 48, 58, 68, and 78?

At 8 You take her to bed and tell her a story.

At 18 You tell her a story and take her to bed.

At 28 You don't need to tell her a story to take her to bed.

At 38 She tells you a story and takes you to bed.

At 48 She tells you a story to avoid going to bed.

At 58 You stay in bed to avoid her story.

At 68 If you take her to bed, that'll be a story!

At 78 What story??? What bed??? Who are you???