"1996-2007, 42-1"

[Wjames]

The drawbridge, of her bikini I would remove the "of" here. Turn the bikini itself into a drawbridge.
Half pulled-down, to that round fully tanned cheek  I don't naturally pause after "pulled-down" - you might want to lose the comma.
To cheek, no tan lines on her tush
Where I put you, but now I must ask "where I put you" seems out of place to me.

Where did you go, caterpillar? of her and my 16
When you went on the long distance walk,
Along my beer bottle's rim, in the park,
Across my hand when I lifted you,
To that connector road of nylon and polyester Very nice stanza.

I knew joy, as we stripped,
And ran, to the water's edge I think the comma's after "stripped" and "ran" are also unnecessary.

There was a graininess to the sand,
Like it would take a long time to go
Through an hour-glass, perhaps get stuck
Making Lake Tahoe timeless, nice.

To be cherished in dividends
As we returned each summer and winter winter is added abruptly here after all the summer images.

It reminded me of when we were 13, 
When we decided to jump, clothed, into the Pacific I don't like the back-to-back "when we's" - you could easily change one of them and lose nothing.
For continuing traditional last cross country practices;
We had dated three times, during the duration 
Of middle school Does "the duration of" add anything? Why not just "during middle school"?

Now, I remember you by going to the negative
Space of where we were, because I still do hold
Those places holy, and I do need reason, 
When looking back on our departures

Butterflies are free, they say, and you are You could lose "they say" - the narrator is saying this, especially because it ties nicely back to the caterpillar thing.
Married and living in someplace where we Very good - the title implies a death, and this little reveal of a break-up makes one reconsider all that went before.
Never went, and the chaos of having known you
is less like the Pacific, and more like really nice line break

The aquarium, famed where you are, the aquarium is great, a little cage metaphor. 
Down in Monterey, where I dare not venture.
The cost of admission is not worth it. I would end the poem here.

I do still call, maybe once every six months,
And you answer about half those times
It's apparent that we've learned to stick
To watching the waves, instead of trying 

To measure our weight against the water. These last five lines do not fit with the rest of the poem to me. Everything before this is all dream-like, while this is just a flat out statement. 

I really liked reading this, thanks for sharing.