I've been staring at the edge of the water
Long as I can remember
Never really knowing why

While on Cairnholm, Abe wanted to go out there and explore and destroy the hollows and the wights so the peculiars could live without needing loops.

I wish I could be the perfect daughter
But I come back to the water
No matter how hard I try

He tries to stay because he knows it'll hurt Miss Peregrine and the other children if he left; but he feels it'll hurt them more if he stayed.

Every turn I take, every trail I track
Every path I make, every road leads back
To the place I know where I cannot go
Where I long to be

He tries hard to stay, but he still keeps thinking shout leaving.

See the line where the sky meets the sea
It calls me
And no one knows
How far it goes
If the wind in my sail on the sea
Stays behind me
One day, I'll know
If I go, there's just no telling how far I'll go

He wants to explore the vast areas of Peculiardom that hasn't yet been explored.

I know everybody on this island
Seems so happy on this island
Everything is by design
I know everybody on this island
Has a role on this island
So maybe I can roll with mine

Obvious stanza is obvious.

I can lead with pride
I can make us strong
I'll be satisfied if I play along
But the voice inside
Sings a different song
What is wrong with me?

He continues to try to stay, but his heart keeps telling him that he has to leave. The longer he stays, the more he wants to hide the voice inside him for the sake of the others.

See the light as it shines on the sea
It's blinding
But no one knows
How deep it goes
And it seems like it's calling out to me
So come find me
And let me know
What's beyond that line?
Will I cross that line?

He really wants to know what's out there and he can't help it; it's his nature.

The line where the sky meets the sea
It calls me
And no one knows
How far it goes
If the wind in my sail on the sea
Stays behind me
One day, I'll know
How far I'll go

He eventually decides to go.