
Interesting. The message is expressed with a certain refinement some would call insincere, but if so, so was Shakespeare, and, after all, you are his head monkey. I use the same kind of expression from time to time. I find the style very attractive: Refined expression in sparse (not minimalist) form. The turns of phrases are nice too.
A few suggestions: S2L1: “nor what may lie behind”. The inverted “know I” sounds a bit too artificial, almost pretentious. S3L1: No comma should be after but. I suspect that an earlier version had “but” on a separate line. That’s ok too, but still, I think no comma. Finally, you might consider combining the first two lines of S3 on one line. It would convey a feeling of summation, and also contrast nicely with the two “kiss” lines.
Alcuin

Tis actually pretty damned sweet. And not the sugary teeth hurting kind. More like apple in a really good curry.
You've used rhyme so well in the first couple of stanzas that I really notice the lack in the third and I'm not sure that's a good thing. Although you alter the form of that third stanza, I would really suggest a rhyme between the first two lines, even if you're not going to continue that 3rd line rhyme. Having the rhyme right the way down the bottom (such/much) just doesn't seem to pack that velvet punch, I'm afraid. You could leave it there, of course, but I'd still suggest sticking in another earlier on. In fact, I'd really prefer to see that 3rd line rhyme continued, even in near rhyme, on reflection. The third stanza, though it's clearly supposed to be "far far too much" is just not sitting well with my senses.

I'm going to add my two cents about S3, because its execution is vital to the poem. Your first two stanzas are very well set up, so I think the key to getting this one right is S3. I think the repetition of "a single kiss from you" is superfluous and I don't really see where it helps you rhythmically either. I say just axe that line and the stanza works better. look at the syllabic use.
8
3
3
4
6
2
1
1
it's working almost like an evens countdown 8, 3+3, 4 but then 6 again. For me it kind of disrupted the momentum.