To me, this song has nothing to do with love. It makes me think of the world around me, and about how much the world has changed. He is reminising about how the world used to be before life became such a hectic place.
"Oh simple thing where have you gone
I'm getting old and I need something to rely on"
This could be talking about how since everything changes so fast it is hard to trust that the things you love most (in this case possibly the nature around him) will be there tomorrow; realizing that nothing in our world is simple anymore.
@Carmela52 same thought \r\n\r\nOverall i\'d it\'s nostalgia. Missing things...