They then joined 200 more friends for a reception at LangLab, an arts- and co-working space in a former furniture factory that is a prime example of the revitalized city Mr. Buttigieg helped transform. Under soft indigo lights on the concrete floor, Mr. Buttigeg and Mr. Glezman danced for the first time as a couple while the band David Wax Museum played a slow-tempo, soulful cover of the 1988 song “When You Say Nothing At All.”

“There are so many things about the community we have a chance to feature,” Mr. Buttigieg said. And in fact the reception was so communitarian that it felt almost crowdsourced: tacos from the Rico Suave food truck; sliders from South Bend’s the Beard & the Boss (even the pork was local, provided by Gunthorp Farms, a fourth-generation Indiana operation); beer from South Bend Brew Works; an assortment of regional cheeses from Oh Mamma’s deli; salads from Cafe Navarre; lattes and coffee from Zen Cafe, housed inside LangLab; artisanal chocolates from local Violet Sky chocolatier; specially created ice cream from the Outside Scoop, flavored with honey harvested from community gardens or whiskey from an Indiana distillery.

“We have a lot of people coming from other places, and we wanted to give them a window and a glimpse into this really cool city,” said Mr. Glezman, who, after relocating to South Bend, moved with Mr. Buttigieg to an old frame fixer-upper they share with a skittish rescue mutt they named Truman.

“People think Indiana must be a drab place to be,” said Mr. Glezman, adding that almost from the outset, serendipity has colored his experience of the old industrial city on the St. Joseph river — a town that, if the pundits have it right, the couple may someday leave behind for Washington.

“On our first date, we went to see the South Bend Cubs play the Great Lakes Loons,” he said, referring to two Class A minor league teams. Afterward, the couple toured the downtown on foot and walked along the St. Joseph River to view interactive illuminated sculptures there known as River Lights. As they headed back to the stadium and their parked cars, they tentatively took each other’s hands for the first time just as postgame fireworks lighted up the night sky.

“Literally, there were fireworks on our first date,” Mr. Glezman said. “It was kind of ridiculous, I know, but I was hooked.”