Yes. It is the biggest romance or light romance or comedy romance cliché in Japanese media.
I'm going to disagree with Kraco and say that it does not work all that well here, the scene with the phone call is far superior to the fireworks festival. In fact, the fireworks scenes, like a few other romance series the past few years, could have been cut entirely and there would be zero difference to this episode. I've outright skimmed through a few in lesser series because nothing unique ever happens at them.
Wakana being attracted to nape of neck isn't a surprise because of his established love for hina dolls. Marin being a glutton has been done as a gag a few times, and Wakana not going out before was really only set up this very episode, but is a repeat of the better-done beach date. The only sub-trope they missed was her getting lost and them...omg, holding hands. At least Marin ruined the moment in-character with the stained tongue.
But falling asleep on the phone together is something at least a little novel. I think I've seen anime only do that once before. Also only using things set up this episode (scary movies) that would have better suited Juju considering we haven't seen Marin being afraid of really anything before, but it at least feels like a very gyaru thing to do. I was kind of expecting him to mumble back another sub-conscious confession, but preferred that it was just a heartfelt one from Marin instead.
The phone call was the right way to end the season. Conclusive enough until the manga gets more material and they can launch another season years later like Chihayafuru does.