Barcelona has two date scenes layered on top of each other. There is the one in the guidebooks, which involves Park Güell at sunset and a paella place near the beach, and there is the one Barcelonins actually use, which involves vermut at 1pm and a long lunch on a Sunday. The second one is better.
The vermut ritual
Fer el vermut, doing the vermouth, is the local pre-lunch ritual on Saturday and Sunday from about noon to 2pm. You go to a bar, order a vermut on tap (red, with an orange slice and an olive), and eat olives, anchovies, mussels, or a pickle on a stick called a banderilla. You do this for an hour, then you go to lunch. As a date, it is unbeatable. It is short, it is cheap (a vermut runs 3 to 4 euros), and the bar is packed with families and old couples, which sets a tone.
Good places to do this: Bodega Quimet on Carrer del Vic in Gràcia. Morro Fi on Carrer del Consell de Cent in the Eixample. La Confitería on Carrer de Sant Pau in El Raval, which is also the prettiest old bar in the city. None of these are secrets, but none of them are touristy either.
The long Sunday lunch
Sunday lunch is the date format Barcelonins take seriously. You sit down at 2pm, you order three courses and a bottle of wine, and you leave at 5pm. Can Vilaró on Carrer del Consell de Cent does old-school Catalan cooking the way it was thirty years ago, including capipota (head and trotter stew) for the brave. Casa Delfín in El Born is more polished but still feels like a neighborhood place. La Cova Fumada in Barceloneta is the original home of the bomba and does not take reservations and closes at 3:15pm sharp. The discipline of getting there on time together is itself a small test of compatibility.
The neighborhood plaça
Locals do not meet in front of the Cathedral. They meet in the plaça nearest their flat. In Gràcia that means Plaça del Sol, Plaça de la Virreina, or Plaça de la Vila. In Sant Antoni it means the area around the market and Carrer del Parlament. In Poble-sec it is Plaça del Sortidor. In the Eixample, where there are no real plaças, people meet at a specific corner of Passeig de Sant Joan, which has been redesigned with wide pedestrian medians and is full of benches and dog walkers.
The move is to meet in the plaça, sit on a bench or order a beer at the terrace, and decide where to go from there. It is unhurried in a way that out-of-towners find disorienting and locals find normal.
Wine bars that are not performances
The natural wine scene here is good and getting better, but the best places are the ones that do not perform it. Bar Brutal in El Born is the obvious one (and reservations are essential), but the wine bars locals slide into without planning are smaller. Vinitus has multiple locations and is reliable. Salvatge in Sant Antoni does small plates and a real list. Monvínic in the Eixample is more serious, with a wine library you can browse. None of these will treat you like you are at a wine event. You order, you drink, you talk.
The Tibidabo move
Driving or taking the Tramvia Blau and Funicular up to Tibidabo for a walk and a coffee is the date Barcelonins do when they want to feel like they are out of the city without leaving it. The amusement park is a separate thing (charming, kitsch, optional). The actual move is to walk around the Temple del Sagrat Cor, look out over the city, and come back down. It takes a couple of hours and costs the price of two metro tickets if you take public transport.
A walk along the Carretera de les Aigües
For the same reason, the Carretera de les Aigües is where Barcelonins go on Sunday morning to run, walk, and bike. It is a flat dirt path along the side of Collserola with the entire city laid out below it. You access it from the Peu del Funicular station on the FGC. As a date it works because it gives you two or three hours of walking and talking with no decisions to make. Bring water. Get a beer at a bar in Sarrià on the way back down.
What locals do not do
They do not eat dinner at 7pm. They do not order sangria. They do not wait in line for Bo de B. They do not take dates to Park Güell unless the date is a child. And they do not, under any circumstances, eat on La Rambla.