On Dec. 4, Mr. Maxwell, feeling stressed out, suggested a hike in the rolling hills of Chester County. Twenty minutes in, they reached a scenic trail with no other hikers around. Mr. Maxwell paused, ready with a speech about loving her with all his heart, and pulled out the ring, which he had stuck in his pocket without a box.

She said yes before he could finish proposing. “I immediately started crying,” she said.

Later that day, a visit to the Downingtown Public Library, where the mayor was to show his support at a fund-raiser, turned into a celebration. “Not to be too ‘Gilmore Girls,’ but we were in this small town and everyone we wanted to share the news with was there and so happy for us,” Ms. Thornburgh said. “I just hope we didn’t upstage the library.”

On Aug. 4, about 100 Downingtown residents trekked to Philadelphia, where Ms. Thornburgh and Mr. Maxwell were married at the Presbyterian Church of Chestnut Hill by the Rev. Cynthia A. Jarvis, with assistance from the Rev. Brigid Boyle. Both are Presbyterian ministers who have known Ms. Thornburgh since she was 6.

The bride, wearing an ivory Nicole Miller column dress, a long veil and her signature eyeglasses, walked down the aisle with her mother, Rebecca McKillip Thornburgh, and her father to meet a broad-smiling Mr. Maxwell. He wore a royal blue suit with a yellow rose boutonniere. Mrs. Thornburgh and Ms. Maxwell each read bible passages from behind a podium before the couple were pronounced married in front of 192 guests. They then raised their joined hands in victory.

Ginny Thornburgh, Ms. Thornburgh’s grandmother, lingered in the church with her husband, Dick Thornburgh, who is now 86 and uses a wheelchair, as guests filed into the church yard to toast the couple. The longtime political wife, has been a mentor to Ms. Thornburgh and a supporter of Mr. Maxwell’s political career. (She and Mr. Thornburgh had contributed to his unsuccessful campaign for the Pennsylvania House of Representatives earlier this year.)

She offered some advice for her granddaughter as she embarked on a life of future campaigns and elections. “In the political world, there’s going to be criticisms,” she said. “Always remember to think about where the criticism is coming from. And love your husband.”