My current boyfriend lives 7 hours away by train, it's not extremely long distance but I've grown accustomed to not being in the same city.
It comes down to the people really, how strong their connection is and personal choices. Personally I think would go insane if I had to see my partner more often then I do, I guess we see each other fairly often though so the distance isn't really a bother, even if he lived in the same city I probably wouldn't see him much more then what I do now.
It can get pricey but in my eyes you can't put a price tag on love, be it family, friends or boyfriend.