"Have you got colour in your cheeks?
Do you ever get that fear that you can't shift
The type that sticks around like something in your teeth?"

This part of the song is questioning whether the person of interest likes him back as he is questioning whether he makes her blush, or just see's him as somebody they can't get rid of, like something stuck in their teeth. Its there, but its unwanted and hard to get rid of.

 

Are there some aces up your sleeve?
Have you no idea that you're in deep?
I dreamt about you nearly every night this week

The reference to the card game relates to the fact that the relationship between the two people described by this song is a game because they do not know what 'card' the other person is going to play next, as its the constant question of 'Do (they) Want to Know' what the other one is feeling. This part of the song also shows that the person likes the person they are singing about a lot because they are very involved with that person as they are 'in deep' and dreaming about them every night. It also suggests his obsession with the person, and its not just a consious thing.
 

How many secrets can you keep?

This line suggests that the singer is asking himself how long he can keep his infactuation a secret, alternativley he could be asking the person why is she keeping secrets.

'Cause there's this tune I found that makes me think of you somehow and I play it on repeat
Until I fall asleep
Spilling drinks on my settee'

The irony that this song will mean this to so many people. The reference to the drink is suggesting to alcholism as a form of mental pain relief.

(Do I wanna know)
If this feeling flows both ways?
(Sad to see you go)
Was sort of hoping that you'd stay
(Baby we both know)
That the nights were mainly made for saying things that you can't say tomorrow day

Here in the song the use of acapella and baritone could represent a conversation between the two people sharing the same feelings and confusion about their relationship. Another hint of alcholism is used here, and darkness and shame is also hinted at in this part of the song because he feels that he can only admit his feelings in the nightime during the dark hours.

 

Crawling back to you
Ever thought of calling when you've had a few?
'Cause I always do
Maybe I'm too busy being yours to fall for somebody new
Now I've thought it through
Crawling back to you

Desperation, lack of power, degrading is all hinted at here because he is putting in all of the effort and doesnt know what he is doing. And alcholism is hinted at again as this person is always on his mind, whether it be sober or drunk, where as it is suggested that it is not the same the other way round. 

So have you got the guts?
Been wondering if your heart's still open and if so I wanna know what time it shuts

Here he is questioning himself again and cant decide what he needs to do. He is also questioning the person, by asking her if she's brave enough to confess her feelings back to him.

Simmer down and pucker up
I'm sorry to interrupt. It's just I'm constantly on the cusp. of trying to kiss you
I don't know if you feel the same as I do
But we could be together if you wanted to

The use of the mid-sentence puncation 'cusp. of trying' this is the singer 'interupting' himself, which represents the confusion and how he is all over the place on the topic of what their relationship is and how desperate he is now to tell the person about the confusion of his feelings.