The Love Elixir of Augusta Stern by Lynda Cohen Loigman

The book starts with the new HR guy at the hospital where Augusta works as a pharmacist hinting that it's time for her to retire (because he's discovered that she's soon turning 80 and not 70, as everyone thinks). She doesn't really want to retire but does and moves to a senior community in Florida. Much to her dismay, soon after her arrival she crosses paths with Irving Rifkin, the guy who worked as a delivery boy at her father's pharmacy in her youth and her first love. You'd think she'd be happy to see him again after all this time, but she is furious. And as the story unfolds in flashbacks we learn what happened to Augusta and Irving all those years ago. It's a charming story and Augusta is a force of nature influenced by her mother who died too young, her respected pharmacist father, and her formidable Aunt Esther, who shared her own wealth of knowledge about healing.