The Sun and the Rainfall Lyrics

Lyric discussion by KofiAnnan 

Cover art for The Sun and the Rainfall lyrics by Depeche Mode

It's a love song. The singer is bored, and the only thing that interests him is his love interest, because she's "unpredictable like the sun and the rainfall".

It's not clear to me what he's bored with; I think it's the current state of his relationship with his love interest, and/or life in general.