I think summer means love with burning passion and ultimate desire, and springtime is the mellow callow sweet but quite harmless period between the lovers. springtime is ever so great but it inevitably leads to summer ("the eyes take on a certain gaze, and leave behind the springtime days"), as the lovers yearns for more and more from each other, and the desires hurt each other ("to play the passion out that haunt you so").
so overall it is the artist's perception of love, that in different phases it can be compared to spring and summer, and when love becomes too strong, it burns the lovers and destroys love itself.
I think summer means love with burning passion and ultimate desire, and springtime is the mellow callow sweet but quite harmless period between the lovers. springtime is ever so great but it inevitably leads to summer ("the eyes take on a certain gaze, and leave behind the springtime days"), as the lovers yearns for more and more from each other, and the desires hurt each other ("to play the passion out that haunt you so").
so overall it is the artist's perception of love, that in different phases it can be compared to spring and summer, and when love becomes too strong, it burns the lovers and destroys love itself.