its not exacly league....more along the line of "socail classes"...however, lines can be broken
the rocker can date the rapper. the nerd can date the prep, and the jock can date the lazy one.
it does happen, sometimes...just it more evolves around the amount of similarities vs differences between the people, and that can often be found in thier "socail class"
thats a little similistic view of looking at it, and i know i missed a few points
"Love is patient, love is kind. It does not envy, it does not boast, it is not proud.
It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs.
Love does not delight in evil but rejoices with the truth.
It always protects, always trusts, always hopes, always perseveres.
Love never fails. "
-1 Corinthians 13:4-8