Why keep coming back to a series of popular but dreadful “horny teen melodramas” from Spain, which have ranged from “vapid but titillating” to “Are you just here for the nudity?“

That rhetorical question can be aimed at the audience for this series, a trilogy which seemingly concludes with “Through My Window: Looking at You.” But that query can be turned back on any critic reviewing all three as well.

Am I just here for the cold-day-in-Catalonia nudity, the sex scenes that break up the monotonous soap opera between them? Nah. I’m back for the same reason I checked back on the films of Cheech and Chong, Tyler Perry, Dakota Johnson or Adam Sandler.

I’m wondering if they get better.

The answer, nailed shut on the third film of this sappy, prolonged romance, is “Alas! No!”

The acting isn’t awful, but the writing has degenerated from insipid to eye-rolling. It’s as if no effort is being made to keep the viewer engaged with what they’re watching on their streaming device between the sex scenes.

To catch us up, Raquel (Clara Galle) is no longer joined-at-the-groin with her rich neighbor, Ares Hidalgo (Julio Peña), an entitled med student (in school in Stockholm in the second film) who steals Raquel’s wifi every time he comes home to Barcelona to his family of pretentiously-named siblings, younger Apolo (Hugo Arbues) and older Artemis (Eric Masip), now in the family business.

But Raquel has been in love with Ares since staring him down “Through My Window.” The fact that she’s with Gregory (Ivan Lapadula) and Ares has married money — Vera (Andrea Chaparro) — can’t stop the love, or sexual assignations.

Apolo may be “with” Daniela (Natalia Azahara), but he’s scratching a different itch on the side.

And bitter Anne (Carla Taus) still hasn’t gotten over the tragedy at the end of “Through My Window: Across the Sea.” Yes, somebody died. If you haven’t seen the second film, I shan’t spoil it for you whilst you catch up.

Raquel has turned her stolen wi-fi romance into a novel that’s coming out, with another book on the way. Hilariously, she’s still got to work part time, dressed as an elf, wrapping gifts in a Barcelona gift shop at Christmas.

Everybody, it seems here, has “an unforgettable ex” and no separation or involvement and even matrimony with anybody else can shake that unfightable urge to climb back “Through My Window.”

And no matter what is going on in everyone’s life, there’s always time for clubbing, Christmas parties and New Year’s Eve blasts.

It’s all a little confusing to drop in on, even if you’ve seen the first two films. But as uncertain as I sometimes was about how this ended up as that and where she/he/they come into this, the ones we should be feeling sorry for here are director Marçal Forés and screenwriter Eduard Sola.

They’re the ones charged with keeping this all straight on an official basis. Do they? Only in a “keep the story going until the next sex scene arrives” sense.

Rating: TV-MA, sex, nudity, alcohol and drug abuse

Cast: Clara Galle, Julio Peña, Natalia Azahara, Hugo Arbues, Eric Masip, Andrea Chaparro, Ivan Lapadula and Carla Taus.

Credits: Directed by Marçal Forés, scripted by Eduard Sola, based on the novel by Ariana Godoy. A Netflix release.

Running time: 1:45