전철: 전(electric)+철(railway) => electric railway = the Metro (subway line).
이호선: pronounces as 2호선 (Metro line #2). The Metro has from 1호선 to 9호선, I think.
So the man and worman's names combine to a commonly used word 전철 이호선, or "Metro Line #2", suggesting the two should be tied together - or 천생연분, "a match made in heaven".