I know I just don't know what you mean by "there are very few happy endings these days" implying that relationships had a tendency to work out better or to last longer in the past or something. But I'm probably just overanalyzing as usual...haha
From a purely statistical point of view they did, marriages were definitely more common, and divorces were less frequent in the not so distance past. Although, I'd agree that is confusing, considering a long lasting marriage may not be synonymous with happy endings, I'm guessing many marriages caused misery because of their confining nature.
p.s. my comment was more persona though, I should have made it clearer, stories such as disney fairytales have happy endings, whereas as an adult I encounter less stories with happier endings, as they tend to be more realistic, which is a shame 🙂