"There's a hole in my soul" - the World's biggest conspiracy theory

Who's up for a game? I'm going to throw some song lyrics at you, and your challenge is to spot the theme. Ready? Let's go.

• Hey, show some love / You ain't so tough / Come fill my little world right up / Right up - Fill My Little World, The Feeling
• There's a hole in my soul / I can't fill it, I can't fill it / There's a hole in my soul / Can you fill it, can you fill it? - Flaws, Bastille
• Well that is it, guys, that is all, five minutes in and I'm bored again - Some Nights, Fun.
• I am lost, I am vain / I will never be the same / Without you - Without You, David Guetta
• The scars of your love remind me of us / They keep me thinking that we almost had it all - Rolling in the Deep, Adele
• I know that I've got issues / But you're pretty messed up too / Either way I found out I'm nothing without you - My Life Would Suck Without You, Kelly Clarkson

What's the verdict? You might have noticed a couple of strands emerging - dissatisfaction with life, and the idea that finding somebody to love will complete you.