I disagree with both of the former posters; I thoroughly enjoy the cavern part of the poem. It's actually my favorite line and I feel it fits very well.
And- while both former readers seemed to get happiness out of the piece I actually felt negativity. It is you that is doing all of the nice things- painstakingly cutting out a thousand hearts and thinking of a thousand things. You are at the house They grew up in. It is you who wakes up first in excitement. The rest of it is both of yours- it seems like it's saying, "what's mine is yours and what's yours as ours". As though you give more than They do. Whether or not this is the case I'm uncertain, but it's definitely what I was thinking about and feeling when I read the piece. What ever the case, good job again.
I will need to revisit this piece. I agree with HisNameIsNoMore about the giddiness. It breathes of an innocence. Young love. A first love when pain from losing it hasn't been experienced. A youthful exuberance. I also agree about the subterranean line. It's abrupt. Drops out of nowhere and hits the reader on the head. I would suggest revising this piece if you haven't already. It evokes good feelings at the start. It would be good to have those feelings follow through to the end without caverns.
I like the warm giddy feeling that this piece inspires. That intangible love. The subject and flow went nice until you reach the forth section. The caves comment doesn't fit, I understand the impact of saying what was said but it just doesn't flow well. It stands out as the odd ball in the group, all the other points coincide with one another. That was the only qualm I had, otherwise keep it up.