Why do japanese (scratch that, japanese men) love the chase but never the rest?
All the popular romance mangas take ages to get the lovers together, riding an eternal "tee hee we like each other but aren't going out so we do the most basic relationship stuff will we ever get together tee hee" only to finish the moment they become a couple.
It's like they slap on a bit of sauce and cheese to the crust of a pizza, end up only eating said crust and tell themselves that was the tastiest, most filling pizza they have ever eaten.