Fiction Apocolypse aftermath

The end of times as we know them. Toxic gas in towns, some sort of disease outbreak that has made people go crazy and turn into cannibals. Survivors of the initial bombings and outbreaks ban together (only a handful of people, less then 20 ideal) to build back and trade with other groups of survivors in distant lands. If a love story between 2 of the survivors (or even multiple romances, even if non-traditional) can be included that would be perfect.