To me "long term" means, we want to make this last til the day we die, basically. I guess to put it simply, I don't ever date just for "fun" I date for a future, I find partners I can see myself with when I'm old, who I can see having a family with, sharing a home. So every relationship is MEANT to be long term, and I believe (and this is only my opinion) that "long term" is the mentality when going into the relationship.
If you plan for just a few years, it's short term. That's why I don't automatically coin the "boyfriend/girlfriend" terms to one another unless I see something that makes me want to be with them forever.