That's very true. There are always big differences between generations. It's an undeniable fact of life. I am in the same generation as the teens in this story as I graduated high school in 2001. I had it a little worse than they did. I was one who had parents even older as my parents were damn near 50 by then as they were born in the early 50's, thus making the divide even bigger.
Okay, now for my thoughts on the chapter. Open relationships are a double-edged sword. Many people are quick to dismiss them as hedonistic debauchery. I don't agree with those sentiments in the least. Sometimes it really can make a relationship stronger. To deny this means to be out of touch with reality in my opinion. Some people are not wired for monogamy. That doesn't make them bad people. That is just how some people are. However, the downside is that there's a risk of one of the partners falling for someone else.
In closing, I thought when I read Chapter 1 that what Robbie wanted was an actual separation, and my reaction was that he was being an ass. Now that I understand what he meant, I can actually see where he's coming from. He wants to regain his youth, and he wants to have new experiences. And as reluctant as he is, Brad wants to expand his horizons as well.