Plenty of other suitable people are available, especially for a romantic relationship. Also expressed as 'not the only pebble on the beach.'
Examples:
- When Bob walked out on Sally, all we could tell her was that he was not the only fish in the sea.
Origin: Expressions using 'fish' used to comfort jilted lovers since early 1500s
Synonyms: not the only pebble on the beach, plenty of fish in the sea