Cinta di antara burung camar dan ikan hanyalah kebetulan
The love between a seabird and a fish is only an accidental occurrence
I have wondered why does the lyric use seabird and fish to describe a love accident. Then I realized, that seabird eats fish, and the only time seabird will meet fish is when seabird flies down from the sky to the sea surface to catch and eats fish. And to have love happens between seabird and fish is purely an accident.
When you say two person accidentally fall in love but are not supposed to be. This metaphor is quite apt.