Dr. Abby Brecher and Gregory Marcus's first date was delayed three months, initially because of a cold sore, and then when Covid hit. Three months after they were introduced, Dr. Abby Brecher and Gregory Alan Marcus finally met in May 2020 for a walk in Riverside Park in Manhattan. "I never dated casually," said Dr. Brecher, 34, a pediatric dentist at Slim Dental Kids in Manhattan. "I wanted to have a lifelong partner. I could have plenty of fun with my girlfriends." Dr. Brecher, also a clinical assistant professor at Touro College of Dental Medicine in Hawthorne, N.Y., graduated cum laude from CUNY Hunter and received a dental degree from Columbia. As far as one of her girlfriends, a periodontist, could tell, Mr. Marcus was also ready to settle down. So at the end of February 2020, with a little help from his father, her friend set them up. (She works with Mr. Marcus's father, an endodontist, who runs a dental practice in Huntington, N.Y.) Mr. Marcus, 37, i...