If you're a fan of USA's Psych, as I am, chances are you went berserk when Shawn and Juliet finally kissed in the summer finale. Fans shrieked and squealed; message boards were overrun with ecstatic crowds; my best friend sent me multiple e-mails in all caps. It was big.

Yet for all the excitement, something felt a little … off.

It had to do with the fact that during the episode, Juliet had already slept with a new boyfriend and now was planning to go on a trip with him. It was in the foyer of this man's home, while he was in another room, that she kissed Shawn.

For some viewers, maybe these circumstances would have added an extra thrill to the proceedings. For many of us, it put a damper on them.

I'm not just dumping on Jules here, because Shawn has been in bed with other women throughout the show. It's not as if these sexual encounters have been overemphasized or graphic. But they happened—and that matters.

I don't just mean it matters in a moral and spiritual sense, though it does. It also matters to the story. In fact, I believe American culture's widespread acceptance of premarital sex is wrecking many of our most popular love stories.

Consider some of your favorite shows, and you may recognize the pattern. Some modern unwritten rule decrees that couples mustn't marry until the end, or nearly the end, of a TV series, because it would ruin the all-important sexual tension. Yet this doesn't preclude sex. They are allowed and even expected to have plenty of that, with each other and with others.

And that can warp a love story. Instead of being able to get emotionally invested in a couple's growing attraction and root for them, we are stymied over and over again as one or the other ends up hopping into bed with someone else. Or we watch them share a bed for so long that actually making a lifelong commitment seems like an afterthought.

The makers of these shows still try to adopt the lingo and feel of traditional romance, sometimes with ludicrous results. I remember my faint incredulity when, late in Gilmore Girls' run, one of the characters claimed that Luke had "waited" for Lorelai for many years. The speech was meant to be significant and moving, but all I could think was, Waited? In what universe does cohabitating with, marrying, and divorcing other women constitute waiting?

Even if the central couple finally ends up at the altar, the audience is often sick of the whole business by the time they get there. We are losing the idea of what "waiting" for the right person really means—of exercising patience, hope, and self-control while moving toward a strong, lasting relationship. Just about the only place on TV to find a romance like that anymore is Turner Classic Movies.

And the more you watch those old-fashioned stories on TCM, where quiet longing or playful bickering takes the place of bed-hopping, the sadder and shoddier the modern stories start to look. In a romantic comedy like The Shop around the Corner, remade decades later as the tedious You've Got Mail, one glance or remark or love letter conveys more genuine passion than a sex scene on HBO (and has the added advantage of being less squirm-inducing).

Even when there's a promiscuous lead character in a classic film, as in An Affair to Remember or, perhaps my favorite romantic film of all, Alfred Hitchcock's Notorious, promiscuity is not without consequences. Sometimes it has grave consequences. And when the character really comes to love another person, an important part of that process is seeing the error of his or her ways and desiring to change his or her way of life. By the end of Notorious, Ingrid Bergman's Alicia, who started out sullen, self-centered, and sexually reckless, has learned to feel and to inspire genuine, selfless love. And that leads to a final breathless, glorious scene with Cary Grant that I've been known to rewind and rewatch three or four times in a sitting.

I rarely feel like doing that with scenes from current TV shows.

Perhaps some of the current trend can be put down to the fact that the very nature of love stories has changed. Nowadays, instead of being found in one self-contained unit like a book, a play, or a movie, most of the love stories that our culture enjoys and discusses are spun out over several years, because that's how TV series work. Television writers, given a beginning but lacking any sort of clear middle or end, have to search for ways to keep the drama going and audience interest high.

But, contrary to the wisdom of Hollywood, forming and breaking and re-forming sexual bonds doesn't seem the best way to do that. Honestly, how many Friends fans do you know who weren't ready for Ross and Rachel to just go away by the end?

Promiscuity in TV shows seems no more conducive to real, heartfelt, long-term romance than it is in real life. Every time I find myself wanting a TV couple to get together, I simultaneously find myself dreading the inevitable emotional and sexual roller coaster that will ensue. Apparently it wasn't enough that the culture of casual sex has done so much to deprive us of good real-life role models; it had to take away all the good love stories, too.

Gina Dalfonzo is editor of Breakpoint and Dickensblog. She wrote "The Good Christian Girl: A Fable" and "God Loves a Good Romance" for CT online.