I keep thinking about 'Station Eleven' by Emily St. John Mandel. While post-apocalyptic, the sci-fi elements are light; it's more about the collapse. Yet, the web of relationships—past and present, romantic and platonic—is the core. The longing for lost loves and the connections forged in the aftermath are what give the book its haunting power.
The traveling Shakespeare troupe in the ruins is a beautiful metaphor for preserving human connection (art, love) after technology falls. The blend is subtle; the 'sci-fi' is the pandemic that changes everything, but the 'romance' is in the enduring, flawed, beautiful ways people try to reach each other across the years.