Sorry IPJ, but you sound a little like those smug 'none of you know real love like I know' people with the above post.
I said nothing of the sort, nor did I intend it, so stop making silly assumptions. I don't know what your relationship is like or anyone else's on this thread, so I don't make any claims about them. I do know lots and lots of people who think the same way I do about love. Love is by no means rare, but it is very distinct. If you're willing to just walk away from a relationship to live in another country, then it's not love.
Yes, I think everyone feels happiness the same way. Of course, it varies in intensity, but the overall physiological and emotional effects are pretty much the same; otherwise, we wouldn't know what the hell we were talking about when we discussed happiness, would we?