There are lot of confounding variables, though. Sex could be down because both men and women have to join the workforce, people live with {their parents for longer, with roommates} because rent is expensive, technology lets parents keep tabs on kids better, etc.
EDIT (to reflect your edit, I believe):
> Also, as for media and marriage I feel like more media is about bad marriages than good ones.
I think that's exactly her point. We only ever talk about "falling in love" and "break up". How many songs can you think of that talk about a resilient relationship? Better yet, how many songs can you think of that talk about a relationship in the past tense and say it was great?
I was thinking about this yesterday. An interesting project would be to filter every top 100 song in the past century for love songs, then look at how many stories are predominantly in the past vs. future tense, and then how many of those say good vs. bad things about the other person in the relationship. My hypothesis is there's most forward-looking of those songs talk about the wonders of love, and the past-looking songs talk about how shitty the relationship was and how they're glad it's over.
Extra credits for whoever buckets the data by decade to see if the trend has shifted.
Really? I'd guess that most past-looking songs take a more mournful angle than an angry one (especially in the past century, what with the various wars), although that could just have to do with my sampling bias.