As for romance novels, I wouldn’t say they’re bad or good. I don’t read those much so I won’t judge the quality. There could be some romance novels that do depict relationships in a realistic, believable manner with all the consequences. I think somebody pointed out on Mike Duran’s blog that the problem’s due to being overshadowed by a singular publisher.
There are publishers other than Harlequin who do publish romance novels but it doesn’t help that Harlequin’s the biggest publisher who bought other publishers (Mills and Boon, Cora Verlag and Silhouette to name a few) that it’s a near monopoly. The fact that Harper Collins bought Harlequin despite owning Avon (what was one of Harlequin’s competitor) kind of worsens things.
To put it this way DC and Marvel have a near-duopoly on superheroes that even if other publishers do the same genre, it’s either almost always exceptional or briefly. Image used to publish a lot of superhero comics but it turns out to have found its true calling outside of it. Archie Comics also does superhero comics but its bread and butter is Archie Andrews and friends.
The Phantom might count but he’s also a lone example in the newspaper cartoon world, especially since Spider-Man’s part of a bigger brand. If you have publishers having a near-monopoly on such a genre that it’s going to be the first thing to come to mind. For every Jane Austen and any realistic, non-escapist romance novel there’s another one published by Harlequin.
The same person also pointed out about the distribution model. Harlequin novels were formerly distributed through vehicles, longer than other books did. Likewise Marvel and DC tend to dominate the comics specialty shops with non-superhero comics faring better in bookstores. (From personal experience.)
That and market saturation, which Marvel and DC did in the 1990s though they still arguably do to some extent. The parallels aren’t exact but close enough to give an idea of romance publishing.