I believe this isn't about a breakup or an existing relationship, I think he's singing about someone that her entwined with, somewhat romantically. He wants more, but it's more of a casual thing and he knows she doesn't want more. This is why he wants to fall asleep before she says something real or before she says how she feels, because he knows it probably won't be what he wants to hear (which is that she cares about him as much as he does). If she says how she feels, then he'll know for sure that she doesn't care, so he'd rather she not say anything and just go to sleep with her. However, he admits that it's always been her and all he can think about is her. Her words come off the wall and go over his head because she's so above his comprehension, in a way.
That's what I get from the song at least.
I believe this isn't about a breakup or an existing relationship, I think he's singing about someone that her entwined with, somewhat romantically. He wants more, but it's more of a casual thing and he knows she doesn't want more. This is why he wants to fall asleep before she says something real or before she says how she feels, because he knows it probably won't be what he wants to hear (which is that she cares about him as much as he does). If she says how she feels, then he'll know for sure that she doesn't care, so he'd rather she not say anything and just go to sleep with her. However, he admits that it's always been her and all he can think about is her. Her words come off the wall and go over his head because she's so above his comprehension, in a way. That's what I get from the song at least.