Thanks to Tinder, Bumble and OkCupid, there are more first dates happening than ever. Is that a good thing? Not for restaurants, according to The Washington Post. In a new piece, restaurants and bar owners discuss how app-driven dating has changed how they do business.

What’s the problem? “They’re moderating how much alcohol they drink,” says Chris McNeal, general manager of Bar Dupont in D.C. He says the couples will often take up residency at a table for a few hours while nursing one happy-hour priced mixed drink or beer.According to Tinder, the app generates a whopping 1.3 million dates a week, many of which are first-daters hoping for in-person attraction over casual drinks, rather than a full meal. Helen Fisher, a biological anthropologist who advises dating behemoth Match (which also owns Tinder, OkCupid, and others) says, “the first date really should be just for cocktails, because you really shouldn’t invest a lot of time or money.”

However, these casual drinks can put a damper on restaurant’s profits, as tables that could be taken up by larger, hungrier parties are often occupied by duos, sometimes for hours on end. McNeal says that some successful first dates will even stick around long after closing: “We’ve been closed for an hour sometimes, and they’re still sitting there.” Other times, couples will make out at the table, oblivious to other diners, or sit around drinking water for another hour after paying the tab.

For more on dating apps, watch this Fortune video:

The increase in two-person parties, compared to larger groups, has caused some restaurateurs to completely change the layouts of their restaurants. Ashok Bajaj, who owns several Washington D.C. spots, ditched booths and installed a larger number of tables for two at his restaurant, Ardeo + Bardeo. “We had 10 tables, and a lot of those tables were for four. Every single table, almost every single night, was filled with couples,” Bajaj says of his decision to redesign the space for Tinder daters.

Though there’s no concrete data available on how first dates have affected dining as a whole, Annika Stensson from the National Restaurant Association says that in the past couple of decades there has indeed been a shift toward smaller dining parties.